The Dialogues of Plato — Translation by David Horan

Plato’s Theaetetus

Persons of the dialogue: Eucleides, Terpsion, Socrates, Theodorus, Theaetetus[1]

142A Euclides: Ah, Terpsion, did you arrive from the country just now or was it some time ago?

Terpsion: Quite some time ago. Indeed I was looking for you around the market place[2] and was surprised that I could not find you.

Euc: Actually, I wasn’t in the city.

Ter: Where were you then?

Euc: As I was going down to the harbour I came across Theaetetus being carried back to Athens from the army camp at Corinth.[3]

Ter: Was he alive or dead?

Euc: Alive, but just barely so. He is in a bad way on account of 142B his wounds, but worse still he has caught the disease that broke out in the army.

Ter: Oh, the dysentery?

Euc: Yes.

Ter: What a man he is! And you say he is in peril of his life.

Euc: A noble and good man, Terpsion; in fact, I also heard some people just now, full of praise for his role in battle.

Ter: That is nothing particularly unusual. Indeed, it would have been much more surprising if he hadn’t played such a role. More to the point, why did the man not stay here in Megara? 142C

Euc: He was in a hurry to get home. Indeed I asked him myself and advised him to stay but he did not want to. So I saw him on his way, and as I was coming back I was reminded of Socrates, and how prophetically he spoke in general, and about Theaetetus in particular. Socrates met him as a young man, I believe, shortly before his own death,[4] and from the company and the discussions he was very pleased with his character. He recounted their discussions to me when I arrived in Athens, and they are well worth hearing, 142D and he said that Theaetetus simply must become famous, if he actually lived long enough.

Ter: Well, it seems he was right about that anyway. But what were these discussions? Can you recount them?

Euc: No, by Zeus, not from memory at any rate. But I made notes at the time as 143A soon as I arrived home, and later on I recollected them at my leisure, and wrote them out. Whenever I went to Athens I would ask Socrates again about whatever I did not remember, and once I got back here, I would make corrections, so that I have now written out almost the entire discussion.

Ter: Yes, I have heard you say that before; and, in fact, I had always intended to ask you to present it, but I have put it off until now. But why don’t we go through it now? Having just come in from the country, I really need to rest.

Euc: Actually, rest is not an unpleasant 143B prospect for me either, as I accompanied Theaetetus as far as Erineos.[5] So let’s go inside and this servant can read to us while we rest.

Ter: Well said.

Euc: Now, this is the book, Terpsion. See the way I wrote the account, not as Socrates recounted it to me, but as a dialogue with the men he was talking to, and he said these were the geometer Theodorus, and Theaetetus. I wished to avoid inserting phrases between the 143C words that were spoken, such as “and I declared”, or “said” whenever Socrates spoke, or again “he concurred” or “he disagreed” whenever the respondent spoke. For this reason I wrote it as direct discourse omitting all such phrases.

Ter: There is no problem with that, Eucleides.

Euc: Well then, take the book and read it, boy.


Socrates: Theodorus, if I cared more about 143D people in Cyrene, I would ask you about its affairs and its populace, and whether any of the young folk there are showing any interest in geometry or any other branch of wisdom. But in fact, my love for them is less than for the Athenians, so I am more eager to know which of our young people are likely to turn out well. I watch out for such young men myself as best I can, and I also ask others once I see that the young want to associate with them. Of course they come to you in no small numbers, and rightly so, as you deserve it in general, 143E and also because of your knowledge of geometry. So if you have come across anyone worthy of report, I would be glad to hear about them.

Theodorus: Well, Socrates, I have come across one such young man among your citizenry, and it is well worth hearing what I have to say about him. Now, if he were handsome, I would be afraid to speak enthusiastically, lest I might seem to have feelings for him. Now, and I hope I don’t upset you when I say, he is not handsome and he is quite like you, with the snub nose and bulging eyes, though they are less pronounced in his case. So I am speaking without fear.

You may rest assured that of all the youths 144A I met previously, and there have been many, I have seen none with such wonderful natural endowments. I never imagined that a man who learns so keenly what others find difficult, could still be extremely modest and also as manly as anyone else, and I do not see this happening elsewhere. But those who are sharp-witted and intelligent, and have good memories like this fellow, are often quick to anger, and are borne hither and thither like ships without ballast being more mad than manly; while the slower sort approach study with some reluctance and are full of 144B forgetfulness. But this youth takes to learning and enquiry so smoothly, steadily and productively, with great modesty, like a stream of silently flowing oil, that you are amazed that one so young could achieve so much.

Soc: That is good news, but which of our citizens is his father?

Theo: I have heard his name, but do not remember it. But look, he is the one in the middle of the group coming towards us. 144C The young man and these companions of his were oiling themselves a moment ago on the running track outside, and they seem to have finished that now, so they are coming in here. See if you recognise him.[6]

Soc: I do recognise him. It is the son of Euphronios of Sunion,[7] a man who was very like the boy you described and generally well regarded; and indeed he also left quite a substantial inheritance. But I do not know the young man’s name.

Theo: Socrates, his name is Theaetetus. 144D However, I believe that the inheritance has been squandered by the trustees, but he is wonderfully generous with his money nevertheless.

Soc: You are describing an excellent man. Ask him to come here and sit beside me.

Theo: I shall. Theaetetus, sit here beside Socrates.

Soc: Yes indeed, Theaetetus, so that I can scrutinise for myself the sort of face I have, for Theodorus says that I have a face like yours. 144E However, if we both had lyres and he said that they were tuned in like manner, would we just believe him or would we find out whether he was speaking as a musician?

Theaetetus: We would find that out.

Soc: We would believe him, would we not, if we discovered he was a musician, but we would be unconvinced if he was not?

Theaet: True.

Soc: Now, I presume that if the similarity of our faces is of any concern to us, 145A we would ask if the speaker was a portrait artist or not.

Theaet: I think so.

Soc: And does Theodorus know portraiture?

Theaet: Not as far as I know anyway.

Soc: Nor geometry either?

Theaet: He certainly does know geometry, Socrates.

Soc: What about astronomy, calculation, music and the various branches of education?

Theaet: Well, I think so.

Soc: Well then, if he says that there is some physical resemblance between us, which he either praises or criticises, it is not worth paying much attention to him.

Theaet: Perhaps not.

Soc: However, what if he were 145B to praise either of our souls for wisdom or excellence?[8] Wouldn’t it be good for the recipient of the praise to exhibit his quality eagerly, while the other watches him closely?

Theaet: Yes certainly, Socrates.

Soc: Now the time has come, dear Theaetetus, for you to give your demonstration, whilst I watch closely. Since, mark my words, Theodorus has praised many strangers and citizens to me, but never in the way that he praised you just now.

Theaet: That’s all very well, Socrates, but take care that he was not speaking in jest. 145C

Soc: No, that is not Theodorus’ way. But do not be hesitant about our agreement by pretending that this man is jesting, in case we have to call him as a witness. No one will doubt his words, so just stand bravely by our agreement.

Theaet: Well, if it seems right to you, that is what I must do.

Soc: Now tell me this: I presume you are learning some geometry from Theodorus?

Theaet: I am indeed.

Soc: 145D And subjects concerned with astronomy and also harmony and calculation?

Theaet: Well, I am trying to, anyway.

Soc: Yes, and so am I, my boy, from Theodorus and others whom, I believe, have some knowledge of these topics; and although I fare quite well with them in most respects, I am perplexed over a minor issue that I must consider with you and our friends here. Does learning not consist in becoming wiser[9] about whatever you are learning?

Theaet: How could it be otherwise?

Soc: And it is on account of wisdom, I imagine, that the wise are wise.

Theaet: Yes.

Soc: And does this differ in any way from knowledge? 145E

Theaet: Does what differ?

Soc: Wisdom! Aren’t people wise in the matters in which they are knowledgeable?

Theaet: Of course.

Soc: So are knowledge and wisdom the same?

Theaet: Yes.

Soc: Well now, this is what perplexes 146A me and I cannot grasp adequately for myself, what knowledge actually is. So now can we speak of this? What do you say? Which of us will speak first? If he goes wrong, he will sit down; and whoever goes wrong after him, will also sit down and be “donkey”, as the children say in the ball game. But whoever comes through without error, will be our king, and may order us to answer any question he likes. Why are you silent? Hopefully I am not being ill-mannered, Theodorus, due to my love of discourse and eagerness to make us engage in discourse, and become friendly and familiar with one another.

Theo: Oh, there is nothing ill-mannered about that, Socrates, 146B but direct one of the young men to respond to you, since I am unaccustomed to such discussions as these, and I am too old to get used to them now. It would be suitable for these chaps and they would make much more progress since, in truth, the young make more progress in everything. So, go on, just as you began; don’t give up on Theaetetus, question him.

Soc: Now, Theaetetus, you hear what Theodorus is saying and I doubt if you would wish to 146C disbelieve him, nor is it proper for a younger man to disobey the directions of a wise man in such matters. Come on, declare clearly and nobly what you think knowledge is.

Theaet: Well, Socrates, I must, since you are both telling me to do so. In any event, if I make any error, you will correct it.

Soc: Yes, certainly, if we are able to.

Theaet: I think that whatever anyone learns from Theodorus is knowledge, geometry and those subjects you listed just now; and so also is cobbling and the other manufacturing skills, each of these and all 146D of these are knowledge and not something else.

Soc: How noble and generous, my friend. You are asked for one thing and you provide many, favouring variety over simplicity.

Theaet: Why do you say that, Socrates?

Soc: Well, perhaps it is nothing, but I shall tell you what I think anyway. Whenever you refer to cobbling, are you talking about anything other than the knowledge of making shoes?

Theaet: Nothing else.

Soc: And what about 146E carpentry? Do you mean anything other than the knowledge of making wooden objects?

Theaet: No, that’s it.

Soc: In both cases, aren’t you defining what it is knowledge of?

Theaet: Yes.

Soc: But, Theaetetus, you were not asked what knowledge is knowledge of, or how many kinds there are; that was not the point. Indeed we did not ask the question from a desire to count them, but we wanted to know what knowledge itself actually is. Or am I making no sense?

Theaet: No, you are absolutely correct.

Soc: Well, consider this also: 147A if someone were to ask us about one of the ordinary things around us, for example, what clay is, would we not be silly to answer: potters’ clay, oven makers’ clay, brick makers’ clay?

Theaet: Surely.

Soc: Firstly, we would be silly to imagine that the questioner understands anything from our answers whenever we say “clay”, whether we add “of modellers” or of any other 147B craftsmen. Or do you think anyone understands any name of anything without knowing what that thing is?

Theaet: Not at all.

Soc: Then neither does anyone understand knowledge of shoe-making who does not know knowledge.

Theaet: He does not.

Soc: So, whoever is ignorant of knowledge, does not understand cobbling or any other skill.

Theaet: That’s it.

Soc: So, when we respond with the name of some skill when we are asked what knowledge is, that is a ridiculous answer. Indeed the answer says “knowledge of something”, and that does not answer the question. 147C

Theaet: So it seems.

Soc: Well then, we seem to be going the long way around instead of answering plainly and briefly. Thus, on the question about clay, we could say, plainly and simply, that it is earth mixed with water, regardless of whose clay it is.

Theaet: Oh, it seems easy when you put it like that, Socrates. However, it is very likely that what you are asking about is like what came up recently in conversation between myself and your namesake here,[10] Socrates. 147D

Soc: Like what, Theaetetus?

Theaet: Theodorus here, was illustrating something about powers to us; showing that a three foot square and a five foot square do not have a common measure with respect to a single foot. He dealt with each number in this way until he reached seventeen and then he stopped for some reason. Now, since the number of powers appeared unlimited, it occurred to us to try to comprehend them into a unity, by which we could refer to all these powers. 147E

Soc: And did you find something like this?

Theaet: I think that we did, but see if you agree.

Soc: Tell me.

Theaet: We divided all number into two. Those that arise by multiplying equal numbers we likened to a square shape and called them both square and equilateral numbers.

Soc: Yes, that’s good.

Theaet: However, between these numbers are all those, such as three and five, which cannot be generated by multiplying 148A equal numbers. These are produced by multiplying greater by lesser or lesser by greater and the sides that enclose them are of different lengths, so we likened them to an oblong shape and called them oblong numbers.

Soc: Excellent, but what did you do next?

Theaet: Whatever lines form an equilateral flat number[11] when they are made into squares, we defined as magnitudes, while the lines whose squares form an oblong flat number we defined as powers, as they do 148B not have a measure, common in magnitude, with the other magnitudes, though the flat numbers they can form do have such a measure. Similar considerations apply to solid structures.

Soc: Well that is excellent, my fellows, and I don’t think that Theodorus will be open

to a charge of perjury.

Theaet: Very well, Socrates, but I would not be able to answer what you are asking about knowledge in the very way I spoke about magnitudes and powers. However, I think that’s the sort of wording you are looking for, so Theodorus may prove false after all. 148C

Soc: Well, suppose he had praised you as a runner, saying that he had never come across a young man who could run like this, and you were then beaten in a race by the champion in his prime, do you think that his praise would be any less true?

Theaet: I do not.

Soc: And do you think that the search for knowledge, in the manner I have just described, is something trivial or a task for those at the pinnacle in every respect?

Theaet: Oh, by Zeus, I really believe it is for those at the absolute pinnacle.

Soc: Well then, be confident about yourself, believe that Theodorus is right, and 148D exert yourself in every way, both in general, and to arrive at an account of what knowledge actually is.

Theaet: If exertion is all we need, Socrates, it will come to light.

Soc: Go on then. Indeed you showed the approach very nicely just now, so try imitating your answer about powers. Just as you encompassed the many powers in a single form, so also describe the many types of knowledge in a single account.

Theaet: Be assured, Socrates, 148E that I have embarked upon this enquiry many times, on hearing reports of the questions you ask. However, I am never able to persuade myself that I have anything useful to say, nor have I heard anyone else speaking in the way you are exhorting me. Then again, I can’t give up the preoccupation either.

Soc: For you are in labour, dear Theaetetus, because you have conceived and are not barren.

Theaet: I don’t know about that, Socrates, I am only describing what I experience. 149A

Soc: How comical! Have you not heard that I am the son of a fine burly midwife named Phaenarete?[12]

Theaet: Yes, I heard that before.

Soc: Now, have you also heard that I practise the same skill?

Theaet: Not at all.

Soc: Well it is true, believe me! But you must not tell everyone else about me, my friend, as they are unaware that I have this skill. And since they do not know this about me they never say it; but they do say that I am very strange and that I make men perplexed. Surely you have also heard that?

Theaet: I have indeed. 149B

Soc: Well, shall I tell you the reason?

Theaet: Yes, certainly.

Soc: Well, if you consider the status of all midwives, overall, you will understand what I mean more easily. Indeed I presume you know that no women, who are themselves still conceiving and bearing children, act as midwives to others, but only those who can no longer bear children.

Theaet: Yes, certainly.

Soc: Artemis is responsible for this, so they say, because she has been allotted responsibility for child-bearing though she is childless.[13] So she did not give the midwife’s role to those who are barren, as human nature is too weak to understand a skill 149C of which it has no experience. Instead, she assigned it to those who are past child-bearing age, in honour of their likeness to herself.

Theaet: Quite likely.

Soc: And isn’t it both likely, and necessarily the case, that the midwives recognise, better than anyone, which women are with child and which are not?

Theaet: Yes, indeed.

Soc: And indeed the midwives are able to arouse the pangs or allay them as 149D they so wish, by administering potions or incantations. They can deliver difficult births, and if they believe the embryo should miscarry, they bring on miscarriage.

Theaet: This is so.

Soc: Well, have you noticed something else about them? That they are the most ingenious match-makers, as they are omniscient when it comes to knowing the types of men with whom various women should consort, to produce the most excellent children?

Theaet: No, I didn’t know that at all.

Soc: Then rest assured that they value this skill more than the cutting of the umbilical cord. Yes, think about it; 149E do you believe that tending and harvesting the fruits of the earth is the same skill as knowing the types of plants that should be sown in various types of soil?

Theaet: It is the same skill.

Soc: And with a woman, my friend, do you think there is one skill dealing with types and another dealing with offspring?

Theaet: That is not very likely.

Soc: No, it is not. However, 150A because men and women are brought together in an improper and unskilled manner, which is called procuring, the midwives shun match-making, as they are respectable women who fear that through involvement in match-making, they may be accused of procuring. Yet proper match-making is somehow a role only for the true midwives.

Theaet: So it appears.

Soc: Such is the role of the midwives, but it is a lesser role than mine. Indeed, it is not the custom of women to bring 150B forth images on some occasions and at other times true offspring that are not easy to distinguish. If women did this, the greatest and noblest task of midwives would be to decide which was true and which was not. Do you not agree?

Theaet: I do, indeed.

Soc: Now, my skill of midwifery is, in general, similar in character to theirs, but it differs by delivering men and not women, and by looking after their souls rather than their bodies when in labour. But the greatest thing about my skill is that it 150C is able to test, in every respect, whether the mind of the young man is bringing forth an image and a lie, or something genuine and true.

Now, I do have this in common with the female midwives: I bring to birth no wisdom. And many people reproach me for this, since I ask questions of others while I myself proclaim nothing about anything, because I have no wisdom. Their reproach is true, but the reason is that the god[14] compels me to act as a midwife and has prevented me from giving birth.

So of course, I myself am not at all wise nor have I any invention that is 150D born of my own soul. However, it is different for those who associate with me. Some of them also appear quite ignorant at first, but as our relationship proceeds, all whom the god allows, progress to a wonderful degree. Such is their own belief and that of others, and it is obvious that they have never learned anything from me; rather, they have discovered, from themselves, much that is beautiful and have brought it to birth. However, both I and the god are responsible for the delivery. 150E The proof is that over the years, many who were ignorant of this regarded themselves as responsible, despised me, and went away sooner than they should, persuaded either by themselves or by others. But once they had left me, they miscarried whatever remained within them through bad company, and destroyed whatever fruits I had delivered from them, through improper care. Placing more value on images and lies than upon the truth, they ended up being regarded as ignorant, both by themselves and by everyone else.

One such person was Aristeides 151A the son of Lysimachus,[15] and there have been many others. If these men ever come back again, imploring my company, with extraordinary imprecations, the familiar daimon[16] forbids me to associate with some of them, while it allows me to associate with others, and these men make progress once more.

Now, my associates have another experience in common with women in childbirth: they are pained and full of distress both night and day, even more than the women, but my skills 151B can arouse or relieve this pain; and that is the plight they are in. But, Theaetetus, some who seem to me to have nothing within them to bring forth, I match-make favourably with someone else; and with god’s help, I guess quite competently, whose company will benefit them, knowing that they have no need for me. I have handed many over to Prodicus,[17] and many to other wise and inspired people.

Now, excellent friend, the reason I am speaking to you at such length is that I suspect, as you yourself believe, that you are pained by something you are carrying within.[18] So come to me, the son of a 151C midwife, who is skilled in the midwife’s art, and strive to answer my questions as best you can. And if I consider something you have been saying to be an image and untrue, and I take it out and discard it, do not be angry with me like a new mother over her child. Indeed many before you, dear friend, had such an attitude towards me, as to actually bite me whenever I take something nonsensical away from them. They do not believe that I do this with good intentions, and they are far from realising that no 151D god ever intends harm towards humanity, nor do I act in this way from ill intentions. But I am not allowed to accept falsehood, or to conceal the truth. So start again, Theaetetus, and try to state what knowledge actually is; and do not say that you are not able, for if god wills it, and you summon up your manhood,[19] you will be able.

Theaet: Well now, Socrates, with such encouragement from you, it would be a disgrace if a man did not strive to the utmost to say what he can. So 151E then, it seems to me that whoever knows something perceives that which he knows; so, for now anyway, it appears that knowledge is nothing but perception.

Soc: Spoken nobly and courageously, my boy: that’s how you should speak when proclaiming your views. Come on, let’s examine it together, and whether it happens to be genuine, or a wind-egg.[20] Are you saying that knowledge is perception?

Theaet: Yes.

Soc: Now, it really seems that you have made no ordinary statement about knowledge, but 152A one that Protagoras also made,[21] though he said the same things in a somewhat different way. He says, as you know, that man is the measure of all things, of those that are, that they are, and of those that are not, that they are not. Indeed I presume you have read this?

Theaet: Yes, I have read it many times.

Soc: Does this not somehow mean that since you and I are men, such as any particulars appear to me, so they are for me, and such, in turn, as they appear to you, so they are for you?

Theaet: Yes, this is what it means.

Soc: Now, a wise man is not likely to talk nonsense, so let 152B us follow his argument. Is it true that sometimes when the same wind is blowing, one of us may be cold while the other is not, or one of us a little cold while the other is very cold?

Theaet: Of course.

Soc: Now, at that time, can we say whether this wind, in itself, is cold or not? Or should we accept from Protagoras that it is cold for the person who is cold, but not so for the person who is not cold?

Theaet: It seems we should.

Soc: And is that how it appears to each person?

Theaet: Yes.

Soc: But does “it appears”, mean “it is perceived”?

Theaet: It does.

Soc: Then appearance and 152C perception are the same in the case of warmth and all such matters. Indeed, how things are perceived, is how things are likely to be for each person.

Theaet: So it seems.

Soc: So perception is always of what is, and it is not false because it is knowledge.

Theaet: So it appears.

Soc: Well then, by the graces, was Protagoras an utterly wise person who spoke this riddle to us common crowd, while he divulged the truth to his disciples in secret?

Theaet: Whatever do you mean by that, Socrates? 152D

Soc: I shall tell you, and this is surely no ordinary account. It states that nothing just by itself is one, nor may you refer to it as some thing, nor as any kind of thing. But if you say it is large, it will also appear to be small; and if you say it is heavy, it will also appear light; and so it is for everything, because nothing is one, or something, or of a particular kind. In fact, everything arises from movement and change and intermingling, and we actually say that these things are, but we are not referring 152E to them correctly; for nothing ever is, but is always becoming.

The entire tradition of the wise, except Parmenides, also agrees about this, including both Protagoras and Heracleitus and Empedocles and the supreme poets from each branch of poetry, Epicharmus of the comic, and Homer of the tragic.[22] And when Homer said: “Ocean is the source of the Gods and Tethys is their mother”, he meant that everything is born from flux and change. Or don’t you think this is what he meant?

Theaet: I do, indeed.

Soc: Is there anyone who 153A could do battle against such a vast army, with Homer as their general, and not become a laughing stock?

Theaet: That would not be easy, Socrates.

Soc: It would not, Theaetetus, as there are also the following cogent indications that the account is correct, since movement produces becoming, and what seems to be, while inactivity produces non-being and destruction. Indeed heat and fire, which actually generate and regulate everything else, are themselves generated from movement and friction, and these are both activities. Aren’t these the origins of fire?

Theaet: They certainly are. 153B

Soc: And indeed the race of living creatures is sprung from the same processes.

Theaet: It must be.

Soc: And isn’t the condition of our bodies corrupted by inactivity and idleness, but preserved for the most part by exercise and movement?

Theaet: Yes.

Soc: And what of the condition of the soul? Isn’t it through instruction and attention, which are activities, that it acquires learning and is preserved and becomes better, while through inactivity, which is both lack of attention, and ignorance, it does 153C not understand anything and forgets whatever it does understand?

Theaet: It certainly does.

Soc: So activity is good for both body and soul, while inactivity is the opposite.

Theaet: So it seems.

Soc: I can tell you more about such matters as absence of wind, and calm seas, where the stillness decays and corrupts things, while different conditions will preserve them. But in addition to this, the ultimate evidence I bring forward is the golden cord that Homer declares to be the very 153D sun itself, and he explains that as long as the heavens and the sun are in motion, all things are, and are preserved among both gods and men. However, should this cease and be tied down, everything would be destroyed and, as they say, the world would be turned upside down.[23]

Theaet: Yes, Socrates, it seems to me that that is exactly what he is explaining.

Soc: Therefore, my friend, you must appreciate to begin with, that in the case of the eyes, what you refer to as white colour is not a separate entity outside of your eyes, nor is it in your eyes, nor should you assign any location to it, for it 153E would then be abiding in that place and would not be in the process of becoming.

Theaet: But how does it work?

Soc: Let us pursue the current argument, by proposing that nothing just by itself is one. And thus, it will be evident that black or white or any other colour, has arisen from the eyes hitting upon the relevant motion. Indeed each so-called colour will be neither 154A that which strikes nor that which is struck, but something that has arisen in between, private to each. Or would you maintain that each colour appears to you just as it does to a dog or any other animal?

Theaet: By Zeus, I would not!

Soc: What about this? Does anything at all appear similar to you and to another person? Are you certain of this? Or are you even more certain that it does not appear the same even to yourself, because you are never in the same state as yourself?

Theaet: That’s even truer than your first example.

Soc: Now, if whatever we 154B measured ourselves by, or touched, was large or white or hot, it would never become different through encountering something else, unless it itself actually changed. But on the other hand, if whatever is measuring or touching was large or white or hot, it would not have become different when another object drew near or underwent some process, while nothing happened to itself. As things stand now, my friend, we are forced so easily into extraordinary and comical utterances, as Protagoras and anyone who tries to make the same point as he does would maintain.

Theaet: What sort of utterances do you mean?

Soc: Take a simple example, 154C and you will know all that I have in mind. Presume there are six dice and you introduce four dice beside them, we say that they are more than the four, indeed one-and-a-half times the four. However, if you introduce twelve dice, the six will be less, in fact, half of twelve; and that is the only acceptable description, or would you accept any other?

Theaet: I would not.

Soc: Well then, what if Protagoras, or someone else, were to ask you: “Theaetetus, is there any way for something to become bigger or more numerous, other than by being increased?” What would be your response?

Theaet: Socrates, if I were to give my immediate opinion on this question I would answer that it is not 154D possible; but based on your previous question,[24] being wary of contradicting myself, I would say that it is possible.

Soc: By Hera, my friend, a good and divine response. However, it seems, that if you do say that this is possible, the consequences of Euripides’ words will befall you; for your tongue will be beyond refutation, but your heart will not.[25]

Theaet: True.

Soc: Now, if you and I were clever and wise and had searched all the contents of our hearts, we would now spend the remaining time probing the abundant resources at our disposal, as we 154E joined in some sort of sophistical contest, banging our arguments against one another. But now, seeing that we are common men, we shall first prefer to review, in their own terms, the exact thoughts that we ourselves are thinking, and whether they seem to us to be concordant with one another, or entirely discordant.

Theaet: Yes certainly, I would prefer that.

Soc: And so would I. Now since that is so, shall we examine ourselves faithfully and patiently, considering 155A once more what these appearances within us actually are? On considering the first of them, I believe we shall say that nothing would ever become greater or less, either in bulk or numerically, as long as it is equal to itself. Isn’t this the case?

Theaet: Yes.

Soc: And the second of them will have us say, that if nothing is either added to or removed from something, it will neither increase nor diminish but it will remain equal.

Theaet: Yes, certainly.

Soc: 155B And won’t the third have us say that nothing can be what it was not before, without becoming, and a process of becoming?

Theaet: It certainly seems so.

Soc: Now, I believe that these admissions are battling with one another in our soul, whenever we discuss the matter of the dice or whenever we say that I, who at my age am neither getting bigger nor going in the opposite direction, am now taller than a youth like you, but later on that I am shorter, over the course of one year. This happens without my frame being reduced but through yours becoming bigger. 155C But note that I am, at a later time, what I was not before, though I have not undergone a process of becoming. But without such a process, it is impossible to become smaller, and without losing any of my bulk I would not have become shorter. And there are, of course, thousands upon thousands of such instances, once we accept all this. I presume you are following, Theaetetus? You actually seem to have some familiarity with such issues.

Theaet: I am, Socrates, and, by the gods, I wonder intensely what they actually mean. And the truth is I sometimes get dizzy from looking at them.

Soc: Well, my friend, Theodorus here 155D seems to have made no poor estimate of your endowments. Indeed this wonder is the particular characteristic of a philosopher, since philosophy has no other origin than this, and it seems that whoever said that Iris[26] was born from Thaumas was not a bad genealogist. But do you now understand why these things are so, based on the statement we are attributing to Protagoras? Or is it not yet clear?

Theaet: It is not clear to me yet.

Soc: Now, will you feel grateful to me if I assist you in a thorough examination of the truth hidden in the thought of a famous man, nay, of famous men? 155E

Theaet: How could I feel anything other than huge gratitude?

Soc: Then look about and take care lest any of the uninitiated is listening in. These are the fellows who believe that there is nothing except what they can hold fast with both hands, and do not accept that activities and processes, and all that is unseen, have a share in being.

Theaet: Oh, yes of course, Socrates, you are describing some quite tough and obstinate characters. 156A

Soc: Yes, my boy, they are indeed most ill educated. But there are others, much more refined, whose mysteries I am about to reveal to you. Now, their first principle, on which hangs all we have been discussing just now, is that all is motion and nothing is excluded from this. The motion has two forms and each is unlimited in multiplicity, though one has an active power while the other is passive. From the mutual intercourse and friction of these two with one another, numerous offspring arise that are limitless in number but always twins. One twin is the perceptible and the 156B other is the perception that constantly accompanies the perceptible and is born along with it.

For the perceptions then, we have such names as seeings and hearings, smellings, cold and hot and, of course, pleasures and pains, desires and fears, as they are called, and others. Indeed those without names are innumerable, and those that have been given names are very numerous. On the other hand, the category of perceptibles has, in turn, a common origin with each 156C of the perceptions, so with variegated seeings there are variegated colours, and the same applies to hearings and sounds, and for the other perceptions the other kindred perceptibles arise. Now, Theaetetus, what does this story tell us about the previous subjects? Can you see?

Theaet: Not very well, Socrates.

Soc: Well, let’s see if we can bring it to a conclusion. It does indeed mean, just as we are saying, that all things are in motion, though some are quick in their movements and others are slow. Now, anything slow has its motion in the same place and relative to whatever comes near, and it produces offspring in this way. 156D But whatever is produced is quicker, and moves from place to place, and its motion naturally involves a place to place movement.

Therefore, whenever an eye and something that can be evaluated by it, draw near and generate whiteness and its associated perception, neither of which would ever have arisen if either of them had encountered something different, there is 156E movement between them at that time. This movement is sight on the part of the eyes, and whiteness on the part of whatever joins in the production of the colour. So the eye becomes full of sight, and then it sees and becomes not sight but a seeing eye, while its partner in the production of colour is saturated in whiteness and becomes, for its part, not whiteness but something white, be it wood or stone or anything else that happens to be coloured in this way.

And this is actually how things work in general. Hard and hot and all else should be understood in the same way, to be nothing just by itself, as we were saying before,157A but in their mutual intercourse everything of every kind arises from the movement, since there is actually no firm basis for thinking that the active or passive is something in isolation. For there isn’t an active until it is joined to a passive, nor a passive until it is joined to an active; and that which joins one thing and is active turns out to be passive when it encounters something else.

And the consequence of all this, just as we were saying at the beginning, is that nothing just by itself is one,[27] but is constantly coming into being 157B with something, and “to be” should be entirely removed from use, not that we haven’t been compelled to use it just now, through habit and ignorance.

But the account of these wise men says we must not do this, nor should we accept the word “something” or “of something” or “mine” or “this” or “that” or any other name that would make it fixed. Instead, we should declare, in accord with nature, that they are coming into being, being produced and being destroyed or changed, since if anyone fixes anything with a word, whoever does this will be easily refuted.

This is also how we should refer to particulars and to aggregates of many; aggregates that are designated as “man” or “stone” 157C and each living creature and form.

Now, Theaetetus, don’t you think this is delightful and so delicious that you could eat it?

Theaet: Well, I don’t know, Socrates; indeed I cannot understand you, and whether you are saying what you believe or testing me out.

Soc: My friend, you are forgetting that I know nothing of such matters, nor do I regard them as my own offspring, since I am barren. However, I am acting as midwife to you, and on this account I am charming you and offering 157D pieces of wisdom for you to taste, until I draw out that belief of yours into the light. Once it is out, I shall evaluate whether it shows itself to be a wind-egg or a genuine birth. So take heart and persist! Answer truly and courageously, and tell us how things appear to you, no matter what I ask you about.

Theaet: Very well, ask me.

Soc: Then tell me if you agree that nothing is good or beautiful, or anything else we just mentioned, but is constantly becoming so.

Theaet: Well, I think so, since it appears marvellously reasonable when I hear you describing it like this and it should be accepted exactly as you have recounted it.

Soc: 157E In that case, let us not leave out anything that is missing from it. What is missing is consideration of dreaming, diseases in general, and also madness; and the extent to which we are said to err in hearing and seeing and in our other perceptions. Indeed you know that in all these cases the account we gave just now seems to be proved wrong by common consent, as false perceptions certainly arise 158A in us under such circumstances, and so for each person the appearances are far removed from what is, but on the contrary, nothing at all that appears to be, is.

Theaet: What you say is perfectly true, Socrates.

Soc: Well then, what argument is left for the one who proposes that perception is knowledge, and that for the person to whom they appear, whatever appears to be, is, in each case?[28]

Theaet: Well, Socrates, I hesitate to say that I don’t know what to say, as you rebuked me for saying that just now. Yet the 158B truth is that I could never dispute that madmen and dreamers have false opinions, when one group believes they are gods, or the others, in their sleep, think that they have wings and are flying.

Soc: Are you not aware of a similar dispute about these and about sleeping and waking in particular?

Theaet: What sort of dispute?

Soc: It is a question that I believe you have heard asked many times. What proof could you provide if someone were to ask, right now, whether we are asleep at present and are dreaming 158C everything that we are thinking, or awake and talking to one another in the waking state?

Theaet: Yes indeed, Socrates, I am at a loss as to what sort of proof should be provided, as they both correspond so closely just like mirrored dance movements. Indeed there’s no reason why our present conversation couldn’t be a discussion with one another imagined in sleep, and, of course, whenever we are asleep and imagine we are recounting dreams, the resemblance of one to the other is uncanny.

Soc: You see then that there is plenty of room for dispute, when it is even disputed whether we are awake 158D or asleep! And indeed, as we spend a similar amount of time asleep and awake, in either state our soul contends that the opinions held at that time are completely true. Consequently, we spend an equal time asserting that this realm is real, and we are equally confident in each case.

Theaet: Entirely so.

Soc: Doesn’t the same argument apply to madness and disease, except that the durations are not equal?

Theaet: Correct.

Soc: And could truth be determined by longer or shorter duration of time?

Theaet: That would be entirely 158E ridiculous.

Soc: Well, have you any other obvious way of demonstrating which of these sets of opinions are true?

Theaet: I don’t think so.

Soc: Then you can hear from me how people talk about these matters, when they designate the appearances of the moment as true for the person to whom they appear. I believe they would ask a question such as: “Theaetetus, would something that is completely different have the same capacity as that from which it is different? And let us not assume that we are asking about something that is the same in one respect but different in another. No, this is completely different.”

Theaet: In that case, it cannot 159A have anything that is the same, either in capacity or anything else whatsoever, once it is altogether different.

Soc: Now, must we not concede that such a thing is also unlike?

Theaet: Well, I think so.

Soc: And if it happens to become like or unlike something, either itself or another, shall we say that in becoming like, it is becoming the same, while in becoming unlike it is becoming different?

Theaet: It must be so.

Soc: And didn’t we say before that there are many, indeed unlimited, active elements and that the same applies to passive elements?

Theaet: Yes.

Soc: And also that anything that is paired with one thing and then with another, will not produce the same things but different things.

Theaet: Yes, certainly. 159B

Soc: Now, let us discuss me and you and things in general, based upon the same argument. Take Socrates when healthy and Socrates when ill, shall we say they are like one another or unlike one another?

Theaet: Are you referring to the unhealthy Socrates as a whole compared to the healthy Socrates as a whole?

Soc: You have understood perfectly. I mean just that.

Theaet: Then, of course, they are unlike.

Soc: And is he different then to the extent that he is unlike?

Theaet: He must be.

Soc: And will you say the same about Socrates asleep 159C and in all the other conditions we mentioned just now?

Theaet: I think so.

Soc: Now, each of the things whose nature is to act upon something else will treat me in one way, when it encounters healthy Socrates, and in a different way, when it encounters unhealthy Socrates.

Theaet: Inevitably.

Soc: Then I who am passive, and this active, will produce different outcomes in each case.

Theaet: Indeed.

Soc: So when I drink wine when healthy, would it appear pleasant and sweet to me?

Theaet: Yes.

Soc: Indeed, based upon what we agreed before, the active 159D and the passive, both moving simultaneously, produce both sweetness and perception. As perception is associated with the passive it turns the tongue into something that perceives, while the sweetness associated with the wine moves about it, and makes the wine both appear sweet and be sweet to the healthy tongue.

Theaet: Yes, what we said before certainly concurs with this.

Soc: But when it encounters the unhealthy Socrates, is that in truth someone different, and not the same person? Indeed it approaches something that is unlike the first.

Theaet: Yes.

Soc: Now a Socrates such as this, along with the draught of wine, gives rise to different 159E outcomes, a perception of bitterness in the region of the tongue, while in the region of the wine, bitterness arises and moves, and so the wine becomes not bitterness but bitter, while I become not perception but a perceiver.

Theaet: Yes indeed.

Soc: So I shall never come to perceive any other thing in this way, for there is another perception of the other thing, and this makes the perceiver different 160A and different in kind. Nor would that which is active towards me ever produce the same thing, or itself be the same sort of thing in its encounter with something different. For having produced another from another, it will become different in kind.

Theaet: This is so.

Soc: Nor indeed shall I become such a perceiver by myself, nor will the active element become different by itself.

Theaet: No, it will not.

Soc: No, but whenever I come to be perceiving I must be perceiving something, for it is impossible to come to be perceiving and yet be perceiving 160B nothing. And whenever sweet or bitter or such like arise, they must arise for some person, for it is impossible to become sweet but sweet to no one.

Theaet: Entirely so.

Soc: What remains for us then, I believe, is that if we are, we are for one another and if we become, we become for one another, since, in fact, necessity conjoins our being, yet it binds us to none of the others, or even to ourselves. So it leaves us bound to one another. Consequently, if someone says that something is, or becomes, he should say that “it is or becomes for someone” or “of something” or “in relation to something”. But he should never say, nor allow someone else to say, that it is or becomes 160C just by itself. That’s what the argument we have been expounding indicates.

Theaet: Entirely so, Socrates.

Soc: Now, since whatever is active towards me, is for me and for no one else, mustn’t I also perceive it and no one else?

Theaet: It must be so.

Soc: So my perception is true for me, as it always belongs to my being, and as Protagoras says, I am judge of the things that are for me, that they are, and also of the things that are not, that they are not.[29]

Theaet: So it seems.

Soc: Now, 160D if I am not being deceived or erring in my thinking about things that are, or things that become, how could I fail to have knowledge of the things that I perceive?

Theaet: There is no way this could happen.

Soc: Knowledge is nothing other than perception: that was an excellent saying of yours! So the various accounts turn out to be the same: Homer and Heracleitus and all their tribe say everything changes like a flowing stream;[30] Protagoras, the wise, says man is the measure of all things; and now 160E Theaetetus says, that since these things are so, knowledge turns out to be perception. Is this so, Theaetetus? Shall we declare that this is like your newborn baby that I have brought to birth? What do you say?

Theaet: It must be so, Socrates.

Soc: So it seems that this is what we have at last produced with some difficulty, whatever it turns out to be. After the birth comes its infant ceremony and we should faithfully carry it around the hearth,[31] in the circle of discussion, on the lookout lest the offspring be unworthy of rearing, as it is 161A false and a wind-egg. Or do you believe that your offspring should be reared, in any case, and not be set aside? Could you endure seeing it tested in argument, and not get violently angry if someone were to take away this, your first-born?

Theo: Socrates, Theaetetus will endure, as he is not at all bad tempered; but, by the gods, do tell us exactly why this is not the case.

Soc: You are a veritable lover of discourse, Theodorus, and it is kind of you to believe that I am some bag of arguments and will easily pull one out to explain 161B that all this is not the case after all. But you do not understand what is going on, that none of these arguments ever comes forth from me, but from the one who is conversing with me, and I know nothing more than the little matter of how to take some argument from someone wise, and receive it appropriately. This is what I shall now try to test from this young man, while I myself proclaim nothing.

Theo: You are putting that very well, Socrates, go ahead and do as you say.

Soc: Now, Theodorus, do you know what amazes me about your friend, Protagoras?

Theo: What is it?

Soc: Well, in general, I am 161C very pleased with his statement that for each person what seems, also is. However, I wonder why he did not say at the beginning of “The Truth”[32] that pig is the measure of all things, or baboon, or some other more unusual creature that has perception, is the measure.[33] He could then have begun to speak to us grandly and contemptuously, demonstrating that while we admired him for his wisdom, like a god, he was actually no more intelligent than a 161D tadpole, let alone another human being. How else can we express this, Theodorus? For if the opinions formed through perception are indeed true for each person, and no one judges a person’s experience better than himself, nor is anyone superior in deciding if the opinion of another is right or wrong, but as we have said many times, each person is, himself, the sole judge of his own affairs, and all these opinions are right and true, what, my friend, is the status of wise Protagoras? Does he properly deserve 161E to be the teacher of others, for huge fees, and should we, in our relative ignorance, have recourse to Protagoras, when each of us is, himself, the measure of his own wisdom? Should we conclude that Protagoras is saying all this in a popularist vein? I am staying quiet about myself and my art of midwifery, for fear of the ridicule we shall incur, as will the conduct of dialectic in its entirety. For it is a vast and vain pursuit, is it not, to undertake the scrutiny and refutation of each other’s notions and opinions, if “The Truth” of 162A Protagoras is true and each of us is right, and this Truth is not a jest uttered from the inner sanctuary of the book.

Theo: Socrates, as you said just now, Protagoras was my friend, so I could not bear to co-operate in his refutation; nor, however, could I oppose you, contrary to my own opinion. So involve Theaetetus once more: he seemed to be responding very appropriately just now.

Soc: Well, Theodorus, if you were to 162B go to Sparta,[34] would you have the right to watch other men, some quite paltry, exercising naked in the wrestling schools and not undress yourself, and expose your own form alongside theirs?

Theo: But why ever not, if they were prepared to trust me and be persuaded by me? Just as I think that I shall persuade you now to let me watch and not drag me into the gymnasium, stiff with age, when you can wrestle with a younger, healthier man.

Soc: Well, 162C whatever pleases you does not displease me, as the proverb says, and so we should go back again to wise Theaetetus. First, Theaetetus, tell us about what we were saying just now, and whether you are surprised at suddenly proving to be just as wise as anyone else, whether man or god. Or would you say that the Protagorean measure applies any less to gods than to humans?

Theaet: By Zeus, I would not. And to answer your question, yes, I am very surprised. Indeed when we recounted how men argue, when they assert that whatever seems, also 162D is, for the person who thinks so, this sounded very good to me, but now the very opposite suddenly turns out to be the case.

Soc: Well, you are young, dear boy, so you listen intently to common talk and you believe it. Indeed, Protagoras, or any of his spokesmen, will reply to these arguments and say: “Noble youths and elders, you sit together indulging in common talk and you bring in the gods, whose 162E existence or non-existence I exclude from my discourses and from my writings.[35] And you say things that the multitude would accept when they hear them, like how terrible it would be if every person differed not, in wisdom, from the cattle in the fields. But proof and necessity never enter your pronouncements, and you rely on likelihood. Yet if Theodorus, or some other geometer, decided to use this method in geometry, he would not be worth one jot. So in such important matters as these, both you and Theodorus must consider whether you will accept arguments based on persuasiveness and likelihood.” 163A

Theaet: No, it’s not right, Socrates, you would not say so and neither would we.

Soc: Then it seems we should think in a different way, based on the word of yourself and Theodorus.

Theaet: A different way, yes, certainly.

Soc: So let’s consider, in this different way, whether knowledge and perception are the same or different. Indeed our entire discussion has somehow been dealing with this question, and for the sake of this, we set in train this plethora of strange topics. Is this not true?

Theaet: Entirely so. 163B

Soc: Shall we agree, then, that whatever we perceive by seeing or hearing is also known at the same time? In the case of foreigners, before we learn their language, shall we either maintain that we do not hear them when they speak, or that we hear them and know what they mean? Or again, if we look at writing with no knowledge of it, shall we assert that we do not see it, or that we know it if we actually see it?

Theaet: Socrates, we shall say that we know this about them anyway: what we see and hear. Their form and their colour are both seen and known, while high 163C and low pitch are heard and also known at the same time. But whatever the scribe or the linguist teaches about these, we neither perceive by seeing nor hearing, nor do we know it.

Soc: Excellent, Theaetetus, and it is best not to argue that point with you, in order that your development may continue. But look, there is another issue looming, figure out how to keep this one at bay.

Theaet: What sort of issue?

Soc: Something like this. If 163D someone were to ask: “Suppose someone comes to know something at a certain time and still retains and preserves memory of that very thing; is it possible for him not to know it, when he is remembering that very thing?” It seems I am being very long-winded, when I just want to ask, if someone who has learned something could be remembering it, but not know it.

Theaet: How could he, Socrates? What you are describing would be bizarre.

Soc: Am I talking nonsense then? But consider this. Don’t you say seeing is perceiving and sight is perception?

Theaet: I do.

Soc: And 163E someone who has seen something, has acquired knowledge of that which he has seen, according to what we said just now.

Theaet: Yes.

Soc: What about this? Do you agree that there is such a thing as memory?

Theaet: Yes.

Soc: And is it memory of nothing or of something?

Theaet: Of something.

Soc: Of things one has learned or perceived, isn’t it memory of things of this sort? Theaet: What else could it be?

Soc: Does a person, on occasion, remember what he has seen?

Theaet: He remembers.

Soc: And does he forget it when his eyes are closed?

Theaet: What an odd thing to say, Socrates!

Soc: 164A Yet we must say so, if we are to salvage our previous argument, otherwise it is eliminated.

Theaet: Yes, by Zeus, that’s what I suspect too; but I don’t quite understand why, so you tell me.

Soc: Well, we say that whoever is seeing comes to have knowledge of that which he is seeing; for we have agreed that sight, perception and knowledge are the same.

Theaet: Yes, indeed.

Soc: And yet the person who sees, and has come to have knowledge of what he has seen, does not see it when his eyes are closed, though he does remember it. Is this so?

Theaet: Yes.

Soc: 164B But “does not see” is the same as “does not know”, if in fact to see is to know.

Theaet: True.

Soc: So it turns out that someone who has come to know something, and still remembers it, does not know it, since he does not see it. And we said it would be bizarre if this were the case.

Theaet: What you say is very true.

Soc: Then an impossible conclusion appears to follow, if someone says that knowledge and perception are the same.

Theaet: So it seems.

Soc: So we have to say that they are different.

Theaet: Very likely.

Soc: 164C Well, in that case, whatever is knowledge? It seems we must discuss this again from the beginning. But, Theaetetus, what on earth are we trying to do?

Theaet: What are you referring to?

Soc: We seem to me like uncouth fighting cocks that turn away and start to crow before we have won a victory over this argument.

Theaet: How do you mean?

Soc: We seem to be satisfied that we have defeated the proposition by coming to an understanding, quite argumentatively, about the similarities between words. We claim to be philosophers, not debaters, yet we behave unconsciously just like these clever fellows. 164D

Theaet: I still do not understand what you are saying.

Soc: Well, I shall try to clarify my own thoughts on the matter, in any case. Now, we were asking if someone who has learned something and is remembering it could fail to know it, and we took the example of a person who has seen something and closed his eyes and is remembering it. We demonstrated that he does not know and at the same time is remembering; and we said that that is impossible. And so, the Protagorean proposition met its downfall, and yours too; your statement that knowledge and perception are the same.[36]

Theaet: 164E So it appears.

Soc: My friend, I believe this would never have happened, if the father of that other proposal were alive, since he would have defended it in all sorts of ways. But now we are mistreating his orphan, and even the trustees, left by Protagoras, have no desire to help it, Theodorus here, being one of them. Well then, for the sake of justice, we ourselves must come to its aid.

Theo: Yes, Socrates, since I was not Protagoras’ trustee, that was 165A Callias, the son of Hipponicus,[37] I somehow turned quickly away from pure discourse and inclined towards geometry, though I would be grateful to you if you came to his aid.

Soc: Well spoken, Theodorus. Now consider the aid I shall proffer. For we could agree to even stranger things than before, if in our usual fashion, we do not pay attention to what we are saying, in our affirmations and denials. Shall I explain this to you or to Theaetetus?

Theo: No, explain it to the company, but let the younger man 165B respond to you, as he will be less shamed if he goes wrong.

Soc: Let me, then, put the most formidable question, that goes something like this: “Is it possible for the same person to know something and not know the thing that he knows?”

Theo: Well, what answer shall we give, Theaetetus?

Theaet: Presumably it is impossible, in my opinion, anyway.

Soc: Not if you propose that seeing is the same as knowing, for how will you respond to the inescapable question, that as they say, traps you in a well-shaft, when some audacious fellow puts his hand over one of your 165C eyes, and asks if you can see his cloak with that covered eye?

Theaet: I think I would say that I cannot see it with that eye, but I can see it with the other one.

Soc: So do you both see, and not see, the same thing at the same time?

Theaet: Yes, in the way we have described it anyway.

Soc: “That is not the question I put to you,” he will say, “I was asking if you do not know the thing that you know, regardless of how this occurs. What is not seen now turns out to be seen, yet you happen to have agreed that seeing is knowing, and not seeing is not knowing. Now work out the conclusion from all this.”

Theaet: 165D I am coming to conclusions contrary to what I was proposing before.

Soc: Yes, my friend, and perhaps you would have had more experiences like this, if someone had gone on to ask you if it is possible to know accurately and dimly, or to know from close up but not from afar, or know the same thing thoroughly and vaguely. There are lots of other questions that a combative professional debater,[38] lying in wait, would ask you, once you propose that knowledge and perception are the same. He would go on to attack hearing and smelling and all such perceptions, and would keep refuting 165E you, relentlessly, until you were in awe of his enviable wisdom and totally entangled by him, and once he had overpowered you, and tied you up, you would be released for a ransom amount that you both agreed upon.

Perhaps you may ask what argument Protagoras will now proffer in defence of his own proposition. Shall we try to state it?

Theaet: Yes, certainly.

Soc: Well no doubt he will say all the things we say 166A in his defence and, I believe, he will also engage in dispute, despising us and saying: “This Socrates, the simpleton! He tries to argue that I am the one who is ridiculous, because some little boy is frightened when Socrates asks him if the same person can remember something and not know it at the same time, and the boy, out of fear, says no because he cannot foresee the consequences. But the position is as follows, O idle Socrates! Whenever you investigate any of my propositions through questioning, then I am refuted, only if the person questioned is defeated 166B while answering exactly as I would answer. But if he answers in another way, it is the actual person who is questioned that is refuted.”

“In this instance, do you think anyone will agree that someone’s present memory of things that he experienced is anything like the experience he was having at the time, and is no longer experiencing? Far from it; or again, would anyone be reluctant to agree that the same person can both know and not know the same thing? Or even, if he was afraid of that proposition, would he ever concede that someone, who is becoming unlike, is the same as he was before becoming unlike? Indeed, if he must be on the lookout for the verbal traps that we each lay, will he ever agree there is a single person, and not a number of persons, and that these become unlimited, 166C as long as the process of becoming unlike actually continues.”

“‘Dear fellow’, he will say, ‘come to terms generously with what I actually propose, and prove if you can, that private perceptions are not arising for each of us, or that if the perceptions that arise are private, what appears is not something that especially arises only for that person, or ‘is’ for that person, if we must use the word ‘is’.

“Now when you refer to pigs and baboons, you not only act like a pig yourself, but you persuade your hearers to treat my writings as you do, which is most improper.”[39]

“Indeed I assert 166D that what I have written is the truth, that each of us is indeed the measure of things that are and are not. However, there are countless differences between one person and another in this respect, because to one person certain things are and appear, while to another, other things are and appear. I am far from denying that there is wisdom or a wise man, but the particular man whom I call wise is one who brings about change, and will make things appear and be good to us, when they both appear and are bad. And 166E again, do not go chasing after this argument based on how I have expressed it, but note this clarification of what I mean. Recall how this was expressed in the earlier conversation,[40] that to a sick man whatever he eats appears sour and is sour, while the opposite appears to be the case, and is the case, for a healthy man. Now we should not portray one as wiser than the other, nor could we; neither 167A should we allege that the infirm man is ignorant because he holds such opinions, nor that the healthy man is wise because his views are different. No, one condition should be changed to the other because the other is better. And in education too, we should effect just such a change from one particular condition to a better one. And while the doctor effects the change with medicine, the sophist does it with his words.[41] Indeed no one ever made a man hold true opinions who previously held false opinions, for it is not possible either to think of things that are not, or of anything outside of what is experienced, and these are always true. I believe, 167B rather, that in a degenerate condition of the soul he holds opinions appropriate to that condition, while in a sound condition of the soul he is made to hold opinions of a different sort, a set of appearances that some naively refer to as true. However, I say that one set is better than the other, but not any truer.”

“My dear Socrates, I am far from referring to the wise as tadpoles, but when it comes to the body I call them doctors, and when it comes to plants I call them farmers. Indeed I say that these farmers engender sound, healthy and true perceptions in the plants, whenever they 167C are sick, in place of the degenerate perceptions, while the good and wise orators make whatever is beneficial rather than degenerate seem right to cities. Now whatever seems right to each city, is good and right for that city, as long as it is believed, but the wise man makes whatever is beneficial rather than degenerate seem right, and be right, for them in each case. And on the same basis, the sophist is wise and worth his large fees, as he too can 167D educate pupils in this manner. And this is how some people are wiser than others while no-one holds a false opinion, and you must put up with being a measure, whether you like it or not, as the salvation of this argument lies in these assertions.”

“Now, if you intend to contradict it all over again, conduct your disputation by presenting a complete argument, or if you prefer to use questions, then use questions, for we should not avoid that method either. Indeed an intelligent person should follow that approach rather than any other.”

“However, heed the precept 167E that your questioning be not unjust, as it is very unreasonable that a man who says that he cares about excellence, should constantly pursue an unfair line of argument. Now it is unfair in this context for someone to carry on this business without distinguishing between disputation and dialogue. In disputation, he may play, and trip up his opponent as often as he can, but in dialectic, he should be serious and also set his partner back on his feet, pointing out to him only those pitfalls into which he has been misled by himself or 168A his former acquaintances. Once you act in this way, whoever spends time with you will blame themselves for their confusion and perplexity, and not you; and they will follow you and love you, and will hate themselves and flee from themselves into philosophy, so that they may become different people, and be freed from what they were before. But if you do the opposite, as do most people, the consequences will be opposite, and instead of philosophers, you will produce followers who hate 168B the subject once they become older.”

“Now, if you listen to me, as I said before, you will settle down, without impatience and aggression, but with a gracious mind, and really consider what precisely we mean when we proclaim that everything is motion, and that for each person, or city, whatever seems, also is. And based on this, you will reflect on whether knowledge and perception are the same, or different, but not as you did just now, on the basis of familiar expressions and terminology 168C that many people employ, in whatever manner occurs to them, causing endless confusion to one another.”

Theodorus, this is the best I can do, from my slender resources, to offer assistance to your friend, but if the man himself were alive he would have defended his offspring more expansively.

Theo: You are joking, Socrates, you have defended the man most vigorously.

Soc: It is nice of you to say so, my friend. But tell me, did you note what Protagoras was saying just now, when he reproached us for directing our arguments against 168D a little child, and using childish fear in refuting his views?[42] He accused us of mere cleverness, extolled “the measure of all things” and urged us to be serious about his proposition.

Theo: How could I fail to notice that point, Socrates?

Soc: In that case, do you think we should heed his injunction?

Theo: I certainly do.

Soc: You see then that all the people here, except you, are small children. So if we are going to obey the man, you and I must be serious about this proposition as we ask and answer 168E one another. Then at least we shall not be accused of boyish sport as we reconsider the proposition.

Theo: What? Surely Theaetetus could follow the scrutiny of a proposition better than many a man with a long beard?

Soc: Not better than you, however, Theodorus. So do not presume that I should make every effort to defend 169A your deceased companion, while you do nothing. Come now, my friend, follow me for a while, at least until we establish whether it turns out that you are the measure when it comes to diagrams, or whether everyone is just like you, and sufficient unto themselves in astronomy and those other subjects in which you are indeed said to excel.

Theo: Socrates, it is not easy for someone to avoid entering into an argument when they are sitting beside you, and I spoke nonsense just now, saying that you would not force me to undress and wrestle as the Spartans do, but would leave the decision up to me: no, you are inclined to the trickery of Skiron![43] Indeed the Spartans 169B ask you to undress or go away, but you behave more like Antaeus, for once someone draws near, you won’t let him go until you have undressed him, and forced him into a verbal wrestling match.[44]

Soc: Theodorus, you have presented an excellent image for the malady that afflicts me; however, I am even more stubborn than the characters you mention. Many a Heracles and Theseus[45] have crossed my path, powerful speakers who have taken me apart, but I shall never back down 169C at all, such is the awful passion for these exercises that has gripped me. So don’t refuse to enter the ring with me, as you will benefit yourself as well as me.

Theo: I have no argument against this, so lead me wherever you wish. I must fully accept the destiny you decree in these matters, and submit to being cross-examined. However, I shall not be able to surrender myself to you, beyond what you are proposing.

Soc: Well, that is far enough. Now, there is one thing you must help me to guard against: we should not slip into a childish form of discussion 169D and be reproached again for this.

Theo: Well, I shall do the best I can.

Soc: In that case, let us take this up again, at the same point as before, and see if we were right or wrong to find fault and criticise this proposition because it made each person self-sufficient in intelligence, and made Protagoras concede[46] to us that in matters of better and worse, some excel over others and these are, in fact, wise. Isn’t this where we were?

Theo: Yes.

Soc: Now, if Protagoras himself were actually present and had agreed, and we had not made this concession on his behalf, in order to help him, 169E there would be no need to seek certainty by resuming the discussion. But perhaps someone will suggest that we lack authority to agree on his behalf and, that it would be better to agree this particular point fully with greater clarity, because whether or not this is the case, is no small matter.

Theo: What you say is true.

Soc: Then let’s get 170A this agreement, as concisely as possible, from his own argument rather than anything else.

Theo: How?

Soc: As follows: “He says, I believe that whatever seems also is, for the person to whom it seems.”

Theo: Yes, he does say that.

Soc: So then, Protagoras, we too are describing the opinions of a man, in fact, of all men, and we declare that there is no one who does not believe himself wiser than others in some respects, while others are wiser in other respects. Indeed in the greatest dangers, whether in battle or disease or storms at sea, they will regard those in authority 170B as gods, who are expected to act as saviours, though their superiority lies in knowledge and in nothing else. And the entire human race is full of people in search of teachers and leaders for themselves, for other creatures and for their activities, while others think themselves capable of teaching and leading. Now in all these cases, what else can we say except that the people themselves believe that there is wisdom and ignorance among them?

Theo: Nothing else.

Soc: Don’t they believe that wisdom is true thought, while ignorance is false opinion?

Theo: Of course. 170C

Soc: So what will become of the proposition, Protagoras? Should we say that people always think what is true, or do they sometimes think what’s true, and at other times what’s false? Indeed it seems to follow from either option, that people do not always think what is true, rather they think both. Consider this, Theodorus, would you yourself, or any follower of Protagoras, be prepared to contend that no one ever believes that someone else is ignorant and thinks falsely?

Theo: No one would accept that, Socrates.

Soc: And yet this is where the 170D proposition inevitably leads, the proposition which states that man is the measure of all things.

Theo: How so?

Soc: Whenever you have formed a judgement by yourself, and you present an opinion to me about something, we should say that this opinion is true for you, based upon Protagoras’ proposition. But don’t the rest of us become judges of your judgement, or do we decide that you always form true opinions? Or do thousands who hold different views oppose you every time, in the belief that your thought and judgement is false?

Theo: 170E They do indeed, by Zeus, Socrates, thousands, and more, as Homer says,[47] who inflict all the troubles of mankind upon me.

Soc: What then? Do you want us to say, that in this case, you are forming opinions that are true for you, but false for thousands?

Theo: It seems that this must follow from the proposition.

Soc: And what about Protagoras himself? Mustn’t it follow, that if he himself did not believe that man was the measure, nor did the world in general, which, in fact, it does not, this truth that the man has written 171A down would be true for no one? However, if he believed it, but the majority did not agree, note firstly, that insofar as more people disagree than agree, to that extent it is more not so than so.

Theo: It must, if it is to be so, and not so, based upon individual opinion.

Soc: Secondly, and this is the cleverest aspect, since Protagoras agrees that everyone thinks things that are, presumably he accepts as true the thinking of those who hold a view contrary to his own thinking, and they think that Protagoras is speaking falsely.

Theo: Yes, certainly.

Soc: 171B Wouldn’t he be accepting that his own thinking is false, if he agrees that the thinking of those who believe him to be speaking falsely, is true?

Theo: He must.

Soc: And yet the opponents do not accept that they themselves are speaking falsely.

Theo: No, they do not.

Soc: While Protagoras again agrees that this opinion is true on the basis of what he has written.

Theo: So it appears.

Soc: Then it will be disputed by everyone, 171C beginning with Protagoras who adds his own agreement whenever he concedes that someone who says the very opposite is forming a true opinion. In that case, Protagoras himself will be accepting that neither a dog, nor any random person is the measure of anything, which he has not learned. Isn’t this so?

Theo: It is so.

Soc: Well, since it is disputed by everyone, the “Truth of Protagoras” would be true for no one, neither for the man himself nor for anyone else.

Theo: We are running my old friend too hard, Socrates!

Soc: But it is not actually clear whether we are running along the right course. Now it is quite likely that the man is wiser than us 171D as he is older, and if he suddenly popped his head up from below, as far as the neck, he would expose me as talking a lot of nonsense; yes, that’s likely, you too for agreeing with me, and then he would dive back down, disappear and be gone. However, I think that we must accept ourselves just as we are, and always state how things seem to us. Accordingly, shouldn’t we declare that any person at all will probably agree that some men are wiser than others, and some are more ignorant than others?

Theo: Well, I think so anyway.

Soc: Yes, the best way to establish the argument is by means of the addition we 171E made as we defended Protagoras. We said, that in most cases such as hot, dry, sweet, and any matters of that sort, as it seems to each, so it also is, for each. However, if the argument is somehow to concede that one person excels over another in some matters, it will prefer to state that when it comes to health and disease it is not every woman, child or beast who is competent to cure itself and realise what is healthy for itself, but in these cases, if any, one person does excel over another.

Theo: That is how it seems to me anyway.

Soc: 172A However, in civic affairs, concerning what’s noble and disgraceful, just and unjust, sacred and profane, whatever each city believes and designates as lawful for itself is, in truth, lawful for that city, and in these matters, no citizen is wiser than another citizen, nor is any city wiser than another city. But when it comes to deciding what is advantageous or disadvantageous for itself, in these cases, if at all, the argument will accept that one adviser is superior to another and the opinion of one city is, in truth, better than that of another, and would never 172B dare to propose that whatever a city believes to be to its own advantage, and designates as such, will certainly turn out that way.

But in the cases I referred to before, just and unjust, sacred and profane, people wish to insist that there is not one of them, which, by nature, has an existence of its own. Instead they say, that whatever seems so to the people becomes true at the time that it seems so, and for as long as it seems so. And, even people who do not entirely hold to Protagoras’ argument, somehow regard this formulation as wisdom.

Argument after argument is descending upon us, Theodorus,172C and larger is emerging from the smaller.

Theo: But haven’t we plenty of free time Socrates?

Soc: It appears that we do. Yes, and I have often reflected, at one time or another, and indeed just now, that those who spend a lot of time in philosophic pursuits naturally prove to be amusing speakers if they end up in courts of law.

Theo: What do you mean by that?

Soc: Those who have been hanging around law courts and such places from their younger years, will surely seem like slaves rather than free-born men when compared to those brought up in philosophy and kindred pursuits. 172D

Theo: But in what way?

Soc: In the sense that the philosophers have the free time, which you mentioned, and they hold their discussions peacefully and in their own time, just as we are doing now, taking up proposition after proposition; indeed we are already on our third.[48] They can do exactly the same as us, if a new topic interests them more than the current one, and they will not care at all whether the discussion be long or short, if only they may encounter what is.

But the other sort, always speak under pressure of time from the 172E water that flows from the clock,[49] and they are not allowed to make speeches on matters close to their hearts. Their opponent stands over them, armed with compulsion and a written document that deals with every issue, from which they cannot depart.[50] Their words are always about a fellow slave, addressed to a master who sits with some charge in his hands, and their disputes are not of a general nature, but the issue is always personal, and his life is often at stake. 173A And in consequence of all this, they become intense and shrewd, knowing how to flatter their master in words, and beguile him in deed, but their souls become small and warped.

Slavishness from youth upwards has removed their growth, uprightness and freedom, and forced them into crooked ways, casting huge perils and trepidations on their still tender souls, and being unable to meet these with justice and truth, they turn directly to falsehood and mutual injustice, and are utterly bowed down and confined. The result is that they turn out as men who, from childhood upwards, are devoid of health 173B of mind, though they believe that they have become clever and wise. So that is the sort of men they are, Theodorus, but what do you want to say about men of our sort? Do you want us to describe them, or leave the matter and return again to the proposition, in case we very much abuse this freedom in switching between topics that we referred to just now?

Theo: Certainly not, Socrates, I want us to describe them! Indeed you expressed this 173C very well: we who move in such circles are not servants to philosophical arguments, but our arguments are just like our slaves and each of them must wait about to be brought to completion whenever we see fit. Nor, in fact, is there any presiding jury or audience imposing penalties or dominating us.

Soc: Well, since that is your view, it seems we should talk about the best of them, for what could anyone say about the mediocre exemplars of philosophy anyway? But the best of them, from their early years, do not even know the way to the market place, nor the 173D whereabouts of the law courts or the council chamber or any other public meeting place in the city. They neither hear the edicts being proclaimed, nor look at the laws when they are written. They would not even dream of involvement with political parties struggling for power, alliances, banquets, or revelling with flute-girls. Whether someone in the city is high-born or low-born, or there is some problem with their ancestry, male or female, concerns him no more than the number of pints in the ocean, as they say. Indeed he does not even know that he does not know 173E about these matters, for he does not avoid them for the sake of reputation, but, in truth, it is only his body that is situated in the city as a visitor, while his mind regards all this as small and insignificant, despises it and takes flight as Pindar says “above the heavens and beneath the earth”, measuring the earth’s vast surfaces, studying the stars and searching out, in every way, 174A the complete nature of each whole, among the things that are, never lowering itself to anything that is near at hand.[51]

Theo: What do you mean by this, Socrates?

Soc: One example, Theodorus, is the case of Thales,[52] who fell into a well as he was gazing up at the stars, and some clever and witty Thracian maid-servant mocked him, saying that he was so eager to know what was in the sky that he forgot about what was right there under his feet. Now the same gibe will apply to everyone 174B whose life is spent in philosophy. Indeed such a person will actually be unaware of his next-door neighbour, not only of what the man does, but whether he is human at all or some other creature. What precisely is man, and what action or response is appropriate to human nature and distinguishes man from other creatures? This is his search and these are the questions he is at pains to answer. I presume you understand now, Theodorus, do you?

Theo: I do indeed, and what you are saying is true.

Soc: Therefore, my friend, such a person 174C will provide amusement, not only to Thracian girls but to the world in general when he meets someone privately or in public, as I said in the beginning, is compelled to discuss matters under his feet or before his eyes, in a courtroom or anywhere else. Through inexperience, he falls into wells, and all manner of perplexity and his clumsiness is terrible, giving rise to a reputation for silliness. Of course, when it comes to slander, he has nothing special to say against anyone, since he does not know anything bad about anyone, having never been interested in such matters; so his inability to contribute 174D makes him look comical. When he hears the praises and the proud boasts of others, he is conspicuous for his unfeigned, genuine laughter that makes him seem ridiculous. And indeed when a tyrant or king is being praised, he believes he is hearing one of the stock-keepers, such as a swineherd or shepherd or some dairyman, being congratulated on a high milk yield, and he thinks that the rulers tend and exploit a more difficult and treacherous creature than the stock-keepers, and that his own busyness 174E renders a king as uncouth and ill-educated within his city walls as any shepherd in a mountain enclosure.

Whenever the philosopher hears that someone has acquired an astonishing amount of land as he has acquired thousands of acres, or even more, he thinks it but a trifle as he is accustomed to viewing the earth in its entirety. And when they sing the praises of families, as though someone is a nobleman if they have seven wealthy grandfathers to their credit, he thinks 175A that the speaker is utterly dim and partial in his view, as his lack of education renders him unable to see the universal, or to figure out that each person has had countless thousands of grandfathers and ancestors: among them, in every case, there were often rich and poor, kings and slaves, barbarians and Hellenes in their thousands.[53] So boasting about a list of twenty-five ancestors stretching back to Heracles, the son of Amphitryon, appears remarkably small-minded to him, and he laughs because they cannot banish petty vanity from their unthinking soul by working out that the twenty-fifth descendant of Amphitryon 175B was such a man as fate decreed he should be, and the fiftieth will be so too.

Now in all these cases, the philosopher will be derided by the world, partly because he seems to be above it all and partly due to his ignorance and perplexity in the particulars of daily life.

Theo: You are describing the situation very comprehensively, Socrates.

Soc: However, my friend, the philosopher may sometimes draw someone upwards, and the person may wish,175C through him, to go beyond “What injustice have I done to you, or you to me?”, in favour of examining justice and injustice themselves, what each is, in itself, and what distinguishes them from all else and from one another; or he may go beyond “Is the king happy?”, “Is a wealthy man happy?”, and inquire into kingship and human happiness and misery, in general, and what sort of states they both are, and the manner in which it is appropriate for a human being to acquire the one and avoid the other. Now, when that shrewd and litigious little soul must, in turn, give an account 175D of all these matters, then the situation is again reversed. He is dizzy and suspended from on high, looking down from the sky above, he is both troubled and perplexed by the strange experience, and his stammering provides no amusement to the girls from Thrace or any uneducated folk, since they are unaware of his plight; no, he amuses all who have been brought up, not in the manner of slaves, but the exact opposite.

There they are, Theodorus, the dispositions of the two types of men. One has been truly brought up, in freedom and leisure, 175E and you obviously call him a philosopher, to whom it is no disgrace to seem simple-minded and of no account, when he encounters the menial tasks of a slave, and doesn’t know how to tidy up bedclothes or make flavoursome food or a flattering speech. The other type can render all such services efficiently and promptly, but knows not how to dress like a free man, or take the harmony of discourse and sing 176A the praises of the life of the gods or of blessed men.

Theo: Socrates, if you were to persuade everyone with your words, as you have persuaded me, there would be more peace and less trouble among men.

Soc: But evils cannot be eradicated, Theodorus, for there must always be something in opposition to the good. Neither can they be situated among the gods, but they must haunt the mortal nature and prowl about the earth. So we should endeavour to flee from here to there as quickly as we can, and to flee is to be as like 176B unto god as we can, and to be like god is to become just and holy with the help of wisdom. However, my friend, it is not very easy to convince people that the reasons we should be pursuing excellence and avoiding vice, are not the reasons the world gives, namely, that we should practise the one and avoid the other, so that we are reputed to be good men and not bad. This actually sounds to me like the idle talk of old women, as they say. So we should speak the truth; which is that god is not unjust in any way whatsoever, but is as just 176C as it is possible to be, and there is no one more like unto god than the person among us who has, in turn, become as just as possible. And therein lies the true measure of a man’s accomplishment, and indeed, his worthlessness and inhumanity, for knowledge of this is wisdom and true excellence, while ignorance of this is folly and manifest vice. Any other seeming accomplishment or wisdom is vulgar in the case of political sovereignty and commonplace when it comes to the other arts.

Therefore, it is best, by far, not to concede to an evildoer 176D or one whose words or deeds are unholy, that his roguery is an accomplishment, for they delight in that reproach and fancy they are hearing, not that they are ridiculous burdens to the earth, but men well fitted for survival in the city. So the truth must be spoken, that they are the sort of people they believe they are not, and all the more so because they do not believe so. Indeed they are ignorant of the penalty for injustice, which is the last thing they should be ignorant of. For the penalty is not what they think it is, scourging or execution, which offenders sometimes avoid 176E suffering; no, this is a penalty that cannot be avoided.

Theo: What penalty do you mean?

Soc: There are two patterns established in what is, one of divine blessedness, the other of godless wretchedness; but they do not see that this is how things are, so through their foolishness and 177A utter mindlessness they fail to realise that because of unjust action, they are becoming like one pattern and unlike the other. So their lives are like the pattern they resemble and that is the penalty they pay. But if we should tell them that unless they set aside their accomplishment, the place that is pure of evils will not receive them when they die, but they will continue in their own pattern of living, evil men among their own kind, they will listen to us as though we were mindless folk addressing clever rogues.

Theo: They certainly will, Socrates!

Soc: 177B Yes, my friend, I know. However, there is one thing that happens to them in private, whenever they must present an argument and accept one in return, about the matters they disparage, and are prepared to persist manfully for an extended duration without running away like cowards. Strangely, my dear friend, they end up dissatisfied with what they themselves are saying, and their eloquence somehow dries up, so that they seem no different from children.

Now, let us call a halt, since this is really a digression, 177C otherwise the continued influx of issues will overwhelm our initial discussion. So if you agree, let’s return to the previous topic.

Theo: A digression like this makes quite pleasant listening, Socrates, as it is easier to follow at my age. However, let us go back to the other discussion again if you think fit.

Soc: Well, I believe we were at a point in the discussion at which we said that the people who declare that being is in motion, and that whatever seems, is, for the person to whom it seems, are in general prepared to assert this confidently. And, especially in the case of justice, they state most emphatically 177D that whatever a city regards as just and decrees to be just, is just, for that city, for as long as the decree remains in force. However, when it comes to what’s good, there is no one so heroic that they would also dare to contend that whatever a city believes to be beneficial for itself and decrees to be so, is actually beneficial for as long as the decree stands, unless he is referring to the mere name, but that would be making a joke of our discussion, wouldn’t it?

Theo: It surely would. 177E

Soc: Yes, he should not refer to the mere name, but should consider the thing that is being named.

Theo: Of course.

Soc: But whatever name it is given, a city surely legislates and enacts all the laws with the aim of maximising the benefit to itself, according to its understanding and ability. Or does it look to some other factor when it legislates?

Theo: Not at all. 178A

Soc: Now, does each city always succeed, or do they also frequently miss the mark?

Theo: Well, I think they also miss the mark.

Soc: Then again, anyone at all might accept these same points more readily, if someone were to ask about the entire category to which benefit also belongs, and that I believe, involves future time. For whenever we legislate, we enact laws that will be beneficial in time to come, and this we would properly designate as “future”.

Theo: Yes, certainly. 178B

Soc: Come on, let’s question Protagoras in this way, or anyone who says the same thing he says. “You say, Protagoras, that man is the measure of everything, including white, heavy, light and everything like that, without exception. For having the criterion of these within himself as he experiences them, so he thinks they are and what he thinks is true for him, and is so for him. Isn’t this so?”

Theo: Just so.

Soc: “And what about future events, Protagoras? 178C Shall we say that he has the criterion of these within himself, and that as he thinks they will be, so they also turn out for the person who thinks so? In the case of heat, suppose a layman thinks he is about to get a fever and will have a temperature, while his doctor thinks the opposite; which opinion should we say that the future will confirm? Or will it confirm both, and for the doctor neither temperature nor fever will arise in the man, while for the man himself there are both?”

Theo: That would be ridiculous.

Soc: Yes, and I think that the farmer’s opinion about wine, rather than the lute-player’s, is superior regarding the sweetness or bitterness 178D of the future product.

Theo: Of course.

Soc: Nor again, would the trainer, judge better than the musician, about what will be discordant or melodious, and what will seem to be melodious even to the trainer himself when he hears it.

Theo: Not at all.

Soc: Or suppose that a meal is being prepared, the judgement of a waiting guest with no knowledge of cookery is inferior to the judgement of the cook about how pleasant the meal will be. So let us not dispute about present 178E pleasure or past pleasure for each person at this stage in the discussion. Let us discuss the future and whether the person himself is the best judge of how things will seem, and what will be, and whether you, Protagoras, could, at any rate, anticipate better than any amateur what speeches would be persuasive to any of us in a courtroom?

Theo: And indeed, Socrates, he professed quite strongly to be better than anyone in that respect anyway.

Soc: Yes, by Zeus, dear friend, otherwise no one would have paid 179A vast sums of money to talk to him. He must have persuaded them that no prophet or anyone else could judge better than himself, how things will be in the future, and how they will seem.

Theo: Very true.

Soc: Well, are legislation and benefit both concerned with the future, and would everyone agree that when a city legislates it must frequently fall short of obtaining the greatest possible benefit?

Theo: Yes, indeed.

Soc: So I think it would be reasonable for us to put it to 179B your teacher that he must agree that one person is wiser than another, and that such a person is the measure, while I, in my ignorance, must not become the measure of anything at all, though the argument, entered on his behalf just now, [54]compelled me to be a measure whether I wanted to or not.

Theo: I think that the proposition is defeated convincingly by that argument, Socrates, and it is also defeated by giving authority to the opinions of others, opinions which state, that in their view, Protagoras’ proposition is not true at all.[55]

Soc: 179C A proposition like this, that every opinion of every person is true, could be disproved in many other ways. But it is harder to grasp the untruth of the immediate experience of each person, from which perceptions, and opinions based upon them, arise. But perhaps I am talking nonsense and these cannot actually be challenged, and those who say that perceptions are self-evident and constitute knowledge may be describing the way things are, and Theaetetus here, was not far wide of the mark 179D in proposing that knowledge and perception are the same.[56]

So we should get closer and inspect this moving-being, as Protagoras’ proxy argument directs us, and tap it and test whether it rings hollow or true. Anyway it is no minor dispute that has arisen over this, and there are quite a few participants.

Theo: Yes, it is far from being minor; in fact, it is spreading all over Ionia, as the followers of Heracleitus lead the chorus for this doctrine most vigorously.[57]

Soc: 179E Well, in that case, dear Theodorus, we should consider it all the more, from its very origin, just as they themselves present it.[58]

Theo: Entirely so, Socrates. And in fact, you could no more conduct a discussion on these Heracleitean doctrines, or the Homeric or more ancient ones you mention, with any of the Ephesians[59] who profess to be experts, than you could with madmen. Indeed they simply keep moving as their doctrines say they should, while staying with a proposition or question, and quietly asking and answering in turn, means less 180A than nothing to them. Well, “less than nothing” is an exaggeration, but there is no rest whatsoever in these men. Rather, if someone asks a question they pull out enigmatic aphorisms, like arrows from a quiver, and shoot them off, and if you seek an explanation of something they have said, you get struck with a new piece of word-play. You will never make any progress with any of them, nor do they get anywhere with one another, but they are very careful not to permit anything certain in a proposition, 180B or in their own souls, believing, I presume, that this is fixity, their worst enemy, which they try as best they can to banish from the world.

Soc: Perhaps, Theodorus, you have seen these men when they are being combative, and have not associated with them when they are at peace. Indeed they are no friends of yours! But I think they do impart such matters, at leisure, to the pupils whom they want to make like themselves.

Theo: By heavens, what pupils? One of these fellows 180C does not become the pupil of another! No, they grow up as they will and each of them takes inspiration from anywhere at all, and one man thinks that the other man knows nothing. As I was about to say, you would never get a rational account from these people, either willingly or under compulsion. Instead, we must investigate the question ourselves as if we were taking on a mathematical problem.

Soc: 180D Well, that sounds reasonable at any rate. Haven’t we taken on the problem from the ancients, who used poetry to conceal from the multitude that the origin of everything else is Oceanus and Tethys, which are streams, and that nothing is fixed?[60] Don’t we have it from the moderns, who, being wiser, put on a more open display, so that even cobblers pick up the wisdom of these men, and give up their silly belief that some things are at rest while others are in motion, learn that everything is in motion, and come to respect these teachers.

But, Theodorus, I had almost forgotten 180E that others, for their part, proclaim opposite views to these,

“All should only be called unmoving” [61]

and whatever else the opponents of these doctrines say, when, like Melissus[62] and Parmenides, they assert that all is one, established within itself with no place to move in.

So what are we to make of all this, my friend? For moving forward, little by little, we have unwittingly ended up 181A between the two sides, and if we do not defend ourselves and escape, we shall pay for it, like men playing in the wrestling ground who are caught by both sides, and dragged in opposite directions across the line. Now, I think we should consider the people we began with, the men of flux, and if they appear to be talking sense, we shall help them to drag us to their side and try to escape the others. However, if the words of those who say that all is at rest, sound truer, we shall fly to them, 181B away from the men who move the unmoving. But if they both appear to be unreasonable, we shall be amusing in our belief that we common folk have something to say, when we have spurned the ancients and the utterly wise men. Well, Theodorus, do you think it is better to keep going in the face of such a danger?

Theo: It would be quite unacceptable, Socrates, not to investigate what each of these groups is saying.

Soc: Let’s investigate it since you are so enthusiastic. Now, 181C I think that our investigation of motion starts by considering the sort of thing people actually mean when they say that all things are in motion. I want to ask whether they mean there is one form of motion, or, as it appears to me, two forms. But this should not be my opinion alone: you should join in too, so that whatever the outcome, we go through the process together. So tell me, when something changes from one location to another or when it revolves in the same place, do you call that motion?

Theo: I do indeed.

Soc: Then let that be one form of motion. But whenever something remains in the same place, 181D yet grows old or goes from white to black or soft to hard or undergoes some other alteration, doesn’t that deserve to be called another form of motion?

Theo: Yes, it must.

Soc: So I am saying that there are two forms of motion: alteration and transposition.

Theo: And what you say is correct.

Soc: So having divided motion in this way, let us now engage in discussion with those who say that all things are in motion, and ask them whether 181E everything exhibits both forms of motion, transposition and alteration, or do some things exhibit both, while some exhibit only one?

Theo: By Zeus, I really cannot say, but I believe they would reply that everything exhibits both.

Soc: Yes, my friend; otherwise, for them, everything will turn out to be both moving and at rest, and it will be no more correct to say that all things are moving than all things are at rest.

Theo: What you say is perfectly true.

Soc: Well then, since they must be in motion, and absence of movement 182A is not possible for anything, everything is continually exhibiting every kind of motion.

Theo: It must be so.

Soc: Now consider the following aspect of their proposition with me.[63] Didn’t we say that they propose something like this about the origin of heat and whiteness and the like: that each of these is moving, along with perception, between the active and the passive, and that the passive becomes a perceiver, but not perception, while the active becomes something with a certain quality, but does not become a quality? But perhaps “quality” seems like a strange term that you do not understand from common usage, 182B so listen to a few examples. Indeed the active element does not become heat or whiteness, but hot or white, and the same applies to all else; for I presume you recall what we said before,[64] that nothing just by itself is one, neither an active nor a passive, but from the mutual association of both of them, perceptions and perceptible things are brought to birth and the active become things with qualities, while the passive become perceivers.

Theo: I remember: how could I forget?

Soc: 182C So let us set aside whatever else they say, whether it accords with this or not, attend only to this one topic of our discussion and ask them: “Do you say that all things are in motion and flux? Is this so?”

Theo: Yes.

Soc: Now are they moving with both motions, which we defined as transposition and alteration?

Theo: They must be, if they are to be completely in motion.

Soc: And if they were only transpositioned, and not altered, I presume we would be able to say what sort of things are being transpositioned in flux, or is this how we should refer to it?

Theo: Yes, this way.

Soc: 182D But since this is not stable either, the flux does not flow white, but changes so that there is also flux of this very whiteness, and it transforms into another colour, lest it be convicted of being stable in this respect. So how can we ever refer to a colour and call it by its proper name?

Theo: Yes, how can we do it, Socrates? Or how can we refer to anything else of that kind, if in fact, it is constantly slipping away as we are speaking because it is in flux?

Soc: But what if we ask about any perception at all, like that of seeing 182E or hearing? Does it ever remain stable as just seeing, or just hearing?

Theo: No, it must not, if in fact all things are in motion.

Soc: So it should no more be referred to as seeing, than as not seeing, nor should any other perception be called perception, rather than non-perception, if all things are in every kind of motion.

Theo: No, it should not.

Soc: And yet Theaetetus and I have stated that perception is actually knowledge.

Theo: Yes, that is what you said.

Soc: So, when we were asked what knowledge is, we gave an answer that is no more knowledge, than not knowledge.

Theo: 183A It seems so.

Soc: The correction to the answer may turn out well for us, who were so keen to show that all things are in motion, so that our original answer would prove to be correct. But now it seems to be the case that if all things are in motion, every answer that anyone gives on any subject is equally correct, whether it proclaims “this is so” or “this is not so”, or, if you prefer, we could say “becomes so”, in case we stabilise these fellows with the word “is”.

Theo: What you say is correct.

Soc: Yes, Theodorus, except that I said “so” and “not so”. But the word “so” should not be uttered, 183B for what is “so” is no longer in motion, nor again should we say “not so”, for it is not in motion either. Instead, those who propose this doctrine must establish some other language, as they do not currently have words appropriate to their hypothesis, unless perhaps “not even thus”, an indefinite phrase, would best suit their purposes.

Theo: Yes, that might well be the most appropriate language for them.

Soc: Well then, Theodorus, we have freed ourselves from your friend and do not yet agree with him that every man is the measure of all things, unless the man has understanding. And we shall not concede that 183C knowledge is perception, not on the basis of the “all things are in motion” approach anyway, unless Theaetetus here has another way of expressing it.

Theo: I am glad you said that, Socrates, for with these issues concluded I too am freed from answering your questions, as we agreed, since the discussion of Protagoras’ proposition has come to an end.

Theaet: No, Theodorus, not until yourself and Socrates have dealt with those who assert 183D that all is at rest, as you proposed earlier.

Theo: Is a young man like you, Theatetus, teaching his elders to be unjust and break their agreements? Prepare yourself instead to respond to Socrates for the remainder of the discussion.

Theaet: I shall, if he wants me to; however, I would much rather listen to the other topic mentioned.

Theo: Calling Socrates into an argument is like calling cavalry to fight on open ground; so just ask, then sit back and listen.

Soc: But, Theodorus, I do not think that I shall be persuaded to do what 183E Theaetetus is asking.

Theo: Why won’t you be persuaded?

Soc: I would be ashamed if we gave only cursory consideration to Melissus and the others who declare that all is at rest, but the shame would be greater in the case of The One – Parmenides. Parmenides appears to me, in Homer’s phrase,[65] as venerable and awful! Indeed I met the man when I was very young and he was very old, 184A and he seemed to me to have depth and total nobility.[66] I am afraid that we may not come to terms with what he said, and that his intention in saying so may escape us all the more. Also the major topic that began this discussion, namely, what exactly knowledge is, may go un-investigated, if we allow this disordered influx of propositions, especially since the subject we are now raising is really immense and would not deserve to be investigated as a mere side-issue. However, if we give it what it deserves, it will obscure our discussion about knowledge. So we should do neither. Instead, we should endeavour, through the midwife’s art, to deliver Theaetetus of his conceptions about knowledge. 184B

Theo: Well, if that’s what you think, that’s what should be done.

Soc: In that case, Theaetetus, let’s consider this additional point in relation to what has been said. You gave an answer whereby perception is in fact knowledge. Is this so?

Theaet: Yes.

Soc: Now, if someone were to ask you: “With what does a person see black and white, and with what does he hear high and low pitch?” I presume you would say “with eyes and with ears”.

Theaet: I would indeed.

Soc: 184C A laxity in the use of words and phrases without any precise scrutiny is, for the most part, quite gentlemanly. Indeed the opposite approach is illiberal, though it is sometimes necessary, as in the present case, where we must take the answer you gave and consider a problem with it. Which answer is more correct, that we see with the eyes or by means of the eyes? Do we hear with the ears or by means of the ears?

Theaet: I think that we perceive by means of eyes and ears, rather than with them.

Soc: 184D Yes, my boy, it would surely be strange if there were lots of senses lodged inside us like soldiers in the Wooden Horse,[67] and everything did not converge on some single form, be it soul or whatever it should be called, by means of which we perceive whatever we do perceive, using the senses as instruments.

Theaet: Yes, I think it is better to put it that way, rather than the other way.

Soc: Now I am being so precise with you about this for the following reason: I want to ask if there is some part of ourselves that is the same, with which we conclude, by means of the eyes, that things are white 184E or black, or by means of the other sense organs, that things have various qualities. If you were asked, would you be able to refer all such processes to the body? But perhaps it is better that you give the answer to the question, rather than me doing the job for you. So tell me, by means of what do we perceive hot, hard, light and sweet? Wouldn’t you propose that it is by means of the body, or is it by something else?

Theaet: Nothing else.

Soc: And are you prepared to agree that whatever can be perceived 185A by means of one faculty, cannot be perceived by means of a different faculty, so you cannot see sounds or hear sights?

Theaet: How could I disagree?

Soc: So, if you have some mental awareness of both, you could not be perceiving them both through only one or the other of the sense organs.

Theaet: I could not.

Soc: Now in the case of sound or colour, do you first realise this about both of them; that they both are?

Theaet: I do.

Soc: And then, that each is different from the other, and the same as itself?

Theaet: Indeed. 185B

Soc: And that both together are two, while each is one?

Theaet: That also.

Soc: And you can also consider whether they are like or unlike one another?

Theaet: Perhaps.

Soc: Now, by means of what do you realise all these things about sights and sounds? Indeed whatever is common to them cannot be apprehended by means of hearing or seeing. And there is also further evidence for what we are saying, for if it were possible to consider whether both are salty or not, you know 185C you could say what you would use to investigate this, and that is evidently neither seeing nor hearing, but something else.

Theaet: Yes, of course, it is the capacity that is exercised by means of the tongue.

Soc: Well expressed! But now, through what organ comes the power to show you what is common to these, and to everything, including what you refer to as “is”, and “is not”, and the various characteristics we were asking about just now? What sort of organ will you assign to all these characteristics, by means of which our perceiving part perceives each of them?

Theaet: You mean being and not being, likeness and unlikeness, same and different, as well as one, and number 185D in general, associated with them. And obviously you are asking about odd and even, and whatever else is associated with them, and you want to know the physical organ by means of which we perceive these with the soul.

Soc: You are following excellently, Theaetetus. Those are the very things I am asking about.

Theaet: Well, by Zeus, Socrates, I am quite unable to answer, except that I do not think, at all, that their source is some particular organ as in the other cases, but it appears to me that the soul 185E herself, by means of herself, investigates what is common to them all.

Soc: You are a beauty, Theaetetus, and not ugly as Theodorus said,[68] for he who speaks beautifully is beautiful and good. Indeed as well as being beautiful, you have done me a favour by saving me from a lengthy exposition, since it seems to you that the soul investigates some things herself, by means of herself, and other things by means of bodily powers. That is actually what I was thinking myself, but I wanted you to think so too.

Theaet: 186A Well, that’s how it appears anyway.

Soc: Now, in which of the categories do you place “being”, for it is surely common to everything?

Theaet: I place it among those things that the soul reaches for just by herself.

Soc: Along with like and unlike, same and different?

Theaet: Yes.

Soc: And what about beautiful and ugly, good and bad?

Theaet: Yes, I think the soul considers the being of these in particular, in relation to one another, as it reflects within herself upon past 186B and present in relation to the future.

Soc: Hold on, won’t the hardness of anything hard and the softness of anything soft be perceived by means of touch?

Theaet: Yes.

Soc: But the soul, by reviewing them and comparing them to another, tries to determine for us their being, that they both are, and their oppositeness to one another, and again, the being of the oppositeness.

Theaet: Yes, certainly.

Soc: Now, as soon as they are born, man or beast is naturally capable of perceiving 186C whatever experiences are referred to the soul by means of the body. But reflection upon the being of these, and their benefit, arises gradually over time, through much application and education on the part of those who attain it.

Theaet: Entirely so.

Soc: Now, can someone encounter truth, who has not even encountered being?

Theaet: Impossible.

Soc: And if someone does not encounter the truth of something, will he ever have knowledge of it?

Theaet: 186D How could he, Socrates?

Soc: So knowledge does not consist of the experiences, but in the process of reasoning about them; for it seems that we are able to apprehend truth and being in this way, but not through the experiences.

Theaet: So it appears.

Soc: Well then, should you call them both by the same name when they are so different?

Theaet: No, that would not be right.

Soc: Then what name do you give to the first, to seeing, hearing, smelling and feeling cold or hot?

Theaet: 186E I call it perception, Socrates. Is there another option?

Soc: So you refer to it collectively as perception?

Theaet: I must.

Soc: And we say it has no share in the apprehension of truth, for it has no share in the apprehension of being.

Theaet: No.

Soc: Then, Theaetetus, perception and knowledge could never be the same.

Theaet: Apparently not, Socrates, and now it really has become abundantly clear that knowledge is different from perception.

Soc: 187A But this was not the reason we embarked upon our discussion. Its aim was to find out what knowledge actually is, not what it is not. Nevertheless, we have made enough progress not to look for it in perception, at all, but in what the soul is exercising when she is concerned, just by herself, with things that are; whatever we call it.

Theaet: Yes, Socrates, and I believe this is called forming opinions.

Soc: Yes, your belief is correct, my friend. And now review this again from the beginning; 187B wipe all our previous discussion from your mind, and see if you have a better perspective, having made this much progress. Say once more what knowledge actually is.

Theaet: Well, Socrates, I cannot say that it is all opinions, since there are false opinions, so knowledge is most likely to be true opinion: take that as my answer. However, as we proceed, if that turns out to be incorrect, as happened just now, we shall try another wording.

Soc: Now that’s how you should speak, Theaetetus, eagerly, rather than answering hesitatingly as you did at first. For if we act like 187C this, there are two possibilities, either we shall find what we are pursuing, or be less inclined to think that we know what we do not know at all, and an outcome like that would actually be no poor recompense. So what are you saying now? Are there two kinds of opinion, one true and the other false, and do you define knowledge as true opinion?

Theaet: I do, that’s how it seems to me at the moment.

Soc: Then is it worth taking up an issue concerning opinion?

Theaet: What sort of issue?

Soc: 187D It is somehow bothering me now, and has done so many times before, generating great perplexity in relation to myself and others, as I am unable to say what actually happens to us and how it happens.

Theaet: What are you referring to?

Soc: The formation of false opinion! Thinking about it now, I am even more hesitant as to whether we should accept it or investigate it in a different way than we did a while ago.[69]

Theaet: Why not, Socrates, if it seems at all necessary? For what yourself and Theodorus said earlier about leisure was quite true, in matters of this sort there is no hurry.

Soc: 187E You are right to remind me, for perhaps this is not a bad time to retrace our steps. Better indeed to accomplish a little, and do it well, than to do a great deal but do it inadequately.

Theaet: Of course.

Soc: How shall we proceed? What do we actually mean? Are we saying that whenever there is false opinion, one of us forms a false opinion, while someone else, by contrast, forms a true one, as this is the natural state of affairs?

Theaet: Yes, that is what we are saying.

Soc: 188A Now isn’t each and everything we encounter either known by us or not known? Indeed, at the moment, I am omitting mention of the intermediate states of learning and forgetting, for they are not relevant to us just now.

Theaet: Well, in that case, Socrates, there is nothing else left in each case, apart from knowing or not knowing.

Soc: Then, whoever forms an opinion, must form an opinion either about what he knows or what he does not know.

Theaet: He must.

Soc: And indeed, isn’t it impossible for someone who has come to know something, not to know that same thing, or for someone who does not know, 188B to know?

Theaet: This must be so.

Soc: So then, does someone who forms false opinions think that things that he knows are not those things, but different things that he knows, and having known both, does he then fail to recognise either?

Theaet: No, that would be impossible, Socrates.

Soc: Well, could he think that things that he does not know, are other things that he does not know, and is it possible that someone who knows neither Theaetetus nor Socrates could take a notion that Socrates is Theaetetus or that Theaetetus is Socrates?

Theaet: 188C How could he?

Soc: Nor indeed does he think that things he knows are somehow things he does not know, nor that things he does not know are things that he knows.

Theaet: No, that would be very strange.

Soc: So how could someone ever form a false opinion? For it is impossible to form an opinion based on anything but these options, seeing that everything is either known or not known, but based on these considerations, it seems impossible to form false opinion.

Theaet: Very true.

Soc: So then, we should not investigate what we are looking for in this way; on the basis of knowing 188D and not knowing. Should we proceed instead on the basis of being and not being?

Theaet: What do you mean?

Soc: Perhaps it’s as simple as this; whoever, on any subject, is thinking things that are not, will inevitably form false opinions, whatever the general state of his mind may be.

Theaet: Quite likely, Socrates.

Soc: But how? What would we reply if someone were to ask: “Is it possible for anyone to do what you are saying, and is there some person who could think what is not, either just by itself, or about some of the things that are?” And it seems we would say 188E in reply: “Yes, whenever he thinks and thinks what is not true.” Is that how we would answer?

Theaet: Just so.

Soc: Now, does that sort of thing happen in any other instances?

Theaet: What sort of thing?

Soc: Well, that a person sees something yet sees nothing.

Theaet: How could he?

Soc: Well then, if he sees any one thing, he sees something that is, or do you imagine that “one” is ever included among things that are not?

Theaet: I do not.

Soc: So, a person who sees any one thing, sees something that is.

Theaet: Apparently.

Soc: 189A And so, a person who hears something is hearing some one thing, something that is.

Theaet: Yes.

Soc: And a person who touches something is also touching some one thing, something that is, since he is touching one.

Theaet: That is also true.

Soc: And doesn’t a person who is thinking, think some one thing?

Theaet: He must.

Soc: And in thinking one thing, he is thinking something that is.

Theaet: I agree.

Soc: So, a person who is thinking what is not, is thinking nothing.

Theaet: So it appears.

Soc: However, a person who is thinking nothing, is not thinking at all.

Theaet: That seems obvious.

Soc: 189B So it is not possible to think what is not, either just by itself or about things that are.

Theaet: Apparently not.

Soc: Then, forming false opinions is different from thinking what is not.

Theaet: Yes, they seem to be different.

Soc: So we have not found false opinion within ourselves based on this approach or the previous one.[70]

Theaet: No, we have not.

Soc: Then does so-called false opinion arise in the following way?

Theaet: How?

Soc: We say that false opinion is a confusion of thought whereby 189C someone says that one of the things that are, is actually another of the things that are, as he has mixed them up in his mind. For in this way, though he always thinks what is, he thinks that one thing is another, falls into error in the investigation, and may properly be said to form a false opinion.

Theaet: What you have just said sounds perfect to me. For whenever someone thinks beautiful to be ugly, or ugly to be beautiful, then he truly is forming false opinions.

Soc: Theaetetus, you obviously hold me in contempt rather than awe.

Theaet: What exactly do you mean?

Soc: I suppose you think I shall not pick 189D you up on this “truly false”, and ask about the “slowly fast” or the “heavily light” or some other opposite, and whether it is possible for something to behave oppositely to itself, and not according to its own nature, but according to the nature of its opposite. Yet I shall let that go, so that your spiritedness will not be in vain. However, you are satisfied, you say, that forming false opinions is a confusion of thought.

Theaet: I am.

Soc: So, according to your opinion, it is possible for the mind to posit that something is different from what it is.

Theaet: Yes, indeed.

Soc: 189E Now, whenever the mind does this, mustn’t it actually be thinking of both things or one or other of them?

Theaet: Yes it must; either both together, or in succession.

Soc: Excellent! But do you call thinking what I call thinking?

Theaet: What do you call thinking?

Soc: Speech that the soul itself carries on with itself about the matters it is considering. I am demonstrating my ignorance here, yet it seems to me that when the soul is engaging in thought, it is really engaging in discourse, 190A asking questions to itself and answering them, and making assertions or denials. But when it has come to a determination, whether slowly, or through sudden realisation and it unwaveringly asserts the same thing, that we designate as its opinion. So then, I, for my part, refer to thinking as speaking, and opinion as speech, not spoken to another person or sounded aloud but delivered in silence to oneself. What do you say?

Theaet: I agree.

Soc: So, whenever someone thinks of one thing as another, he also seems to be telling himself that one thing is the other.

Theaet: 190B Indeed.

Soc: Now, try to recall if you have ever said to yourself that beauty is most assuredly ugly or that injustice is just. In short, consider whether you ever tried to persuade yourself that one thing is, in fact, another. No, on the contrary, you have never dared, even in your sleep, to say to yourself that odd is even or anything of that sort.

Theaet: What you say is true.

Soc: 190C And do you think that anyone else, sane or insane, ever seriously tried to tell himself, with any conviction, that an ox must be a horse or that two must be one?

Theaet: By Zeus, I don’t think so.

Soc: Now, if speaking to yourself is thinking, no one who speaks and thinks of two things, and is apprehending both with the soul, would say or think that one is the other. And you must allow me to use that expression, for what I mean is that 190D nobody thinks that ugliness is beautiful, or anything else of that sort.

Theaet: Yes, Socrates, I shall allow it and I agree with what you say.

Soc: So, when thinking of both, it is impossible to think that one is the other.

Theaet: So it seems.

Soc: However, thinking about only one, and not thinking of the other at all, he would never think that one is the other.

Theaet: What you say is true, for in that case he would also have to be apprehending the one he is not thinking about.

Soc: So confusion of thought is not 190E possible, either through thinking of both of them, or of one of them. So then, anyone who defines false opinion as thinking that one thing is another, would be talking nonsense, for there is evidently no false opinion in us either, on this basis, or on the basis of our previous discussions.

Theaet: It seems not.

Soc: However, Theaetetus, if we cannot show that there is false opinion, we shall be forced to admit a number of absurdities.

Theaet: What sort of absurdities?

Soc: I shall not tell you until I have tried to explore this in every way possible. Indeed I would be ashamed on our behalf, if in our present difficulty, we were forced 191A to agree with anything I am saying. However, if we find what we are seeking, and become free, then we shall discuss this as something that happens to others, while we stand aloof from the ridicule. But if we become utterly perplexed and humbled, I think we shall surrender to the argument and let it walk on us and do with us as it will, as though we had come down with an illness. Now listen, I find there is still one way of enquiry open to us.

Theaet: Just tell me.

Soc: I say that we were wrong when we agreed that it is impossible for someone to be deceived and think that the things that he knows are 191B things he does not know, for, in a way, this is possible.

Theaet: You are expressing what I suspected at the time, when we said that such a thing could happen. Is it that I, who know Socrates, see someone else at a distance whom I do not know and believe that person to be Socrates, whom I do know? For what you describe could happen in that way.

Soc: Didn’t we reject that idea, because it made out that we do not know the things we know when we have known them?

Theaet: Yes, certainly.

Soc: Well, let’s not propose that but the following, which may be somewhat 191C acceptable to us or may challenge us. But really, we are in such a state, that we must thoroughly test every turn of an argument. Consider whether this makes sense: is it possible to learn something that you did not know previously?

Theaet: It is indeed.

Soc: And then something else, and so on?

Theaet: Why not?

Soc: Now assume, for the sake of the argument, that there is a block of wax in our souls, larger in some, smaller in others, some made of purer wax, others of more impure wax, some harder, 191D others softer, while there are others with the proper balance.

Theaet: I am assuming this.

Soc: Let us declare that this is indeed a gift from Memory, the mother of the Muses,[71] and that whatever we may wish to remember of what we see, or hear, or think up for ourselves, is stamped on the wax, like impressions on wax seals, by holding the wax under the perceptions or concepts. Whatever is imprinted is remembered and known for as long as its image may endure, while anything that is erased or that cannot get imprinted is forgotten or not known. 191E

Theaet: Let’s accept that.

Soc: Well, consider whether someone who has knowledge of things, and is considering something he has seen or heard, could form a false opinion in such a manner.

Theaet: In what manner?

Soc: By believing that things that he knows are, at one time, things that he knows, and, at another, things he does not know, occurrences that we improperly agreed to be impossible in our previous discussion.

Theaet: And what do you say now?

Soc: 192A We must begin discussing the issues again, making the following distinctions. It is impossible for a person to believe that something he knows and has in memory in the soul, and that he is not perceiving, is another thing he knows and whose wax stamp he also possesses, though he is not perceiving it. Nor again, can he believe that what he knows is something he does not know, and whose wax impression he does not possess. Nor could he think that something he doesn’t know is another thing he does not know, nor something he does know. Neither could he imagine that something he is actually perceiving is another thing he is perceiving, nor that something he is perceiving is something he is not perceiving. Nor that something he is not 192B perceiving is something else he is not perceiving, nor something he actually is perceiving.

And furthermore, to believe that something he knows and is perceiving, and whose wax impression accords with his perception, is, in fact, another thing he knows and perceives and whose impression accords with the perception, is even more impossible, if that is actually possible, than the other instances. And he cannot believe that what he knows, and perceives, and remembers properly, is another thing he knows, nor another thing he 192C perceives. Nor again, can he think that what he neither knows nor perceives, is something else he neither knows nor perceives. Nor that what he neither knows nor perceives, is something else he does not know. Nor that what he neither knows nor perceives, is something else he does not perceive.

All these instances compete in their inability to form any false opinion in anyone. Indeed it is in the remaining instances, if anywhere, that false opinion must lie.

Theaet: In what instances? Perhaps I would learn more from them, for at the moment I am not following.

Soc: In cases where someone knows, but thinks the things are other things that he knows and perceives, or that he does not know but yet perceives. Or where he thinks what he knows 192D and perceives, are other things he knows and perceives.

Theaet: Now I am even more adrift than before.

Soc: Well, listen to this once more. I know Theodorus, and I remember within myself what he is like, and the same applies to Theaetetus. At certain times I see them and sometimes I do not. At times I touch them and other times not, or I hear them, or have other perceptions of them, while at other times I have no perception of them whatsoever. But do I remember you, nonetheless, and do I know you within myself?

Theaet: 192E Yes, certainly.

Soc: Now this is the first point I wish to make clear, that someone can perceive or not perceive the things he knows.

Theaet: True.

Soc: And in the case of things he does not know, he frequently cannot perceive them either, but often he can only perceive them.[72]

Theaet: This is true also.

Soc: 193A Let’s see if you can follow me better now. If Socrates knows Theodorus and Theaetetus, but sees neither of them, nor has he any other current perception of them, he would never form an opinion within himself that Theaetetus is Theodorus. Am I making any sense?

Theaet: Yes, this is true.

Soc: Now this was the first of these instances I referred to.[73]

Theaet: It was indeed.

Soc: Then the second instance is that knowing one of you, not knowing the other, and perceiving neither of you, I would never think that the one I know is the one I do not know.

Theaet: Correct.

Soc: 193B And thirdly, neither knowing nor perceiving either of you, I would not believe that one whom I do not know is another whom I do not know. Now assume you have heard again all the previous instances in which I never form a false opinion about you and Theodorus, if I know you both, or do not know you both, or if I know one and not the other. And the same argument applies to perceiving. Do you follow?

Theaet: I follow.

Soc: Then what remains is the formation of false opinion in cases where I know you and Theodorus and have the imprints of both of you in that wax, like 193C impressions from seals. Seeing you both from afar, but not very well, I hurry to match your particular imprint to your particular visual appearance by fitting it precisely onto its own trace in memory,[74] in order to bring about recognition. But I get these wrong, and just like people who put their shoes on the wrong feet, I swap them around and set the appearance of one against the imprint of the other. Or my error 193D is like what happens to the appearance of things in mirrors where left turns into right, and it is in these cases that varieties in opinion, and false opinion, occur.

Theaet: That is quite likely, Socrates. You are giving a wonderful account of what happens to opinion.

Soc: There is also the case where I know both of you and I am perceiving one and not the other, but my perception of the former does not accord with my knowledge. This is the case I was describing earlier, when you did not understand me.

Theaet: No, I did not.

Soc: Well, I was saying that if you know someone and perceive 193E them and your knowledge of them accords with your perception, you will never think they are someone else whom you know and perceive, the knowledge of whom also, in turn, accords with your perception. Was that the point?

Theaet: Yes.

Soc: What remains, I presume, is the current formulation, in which we say that false opinion arises for someone who knows both of you, and sees or has some other perception of both 194A without having the wax imprints in accord with his perception of them, and so he shoots wide of the target, like a poor archer, and misses the mark, and we have come to refer to this as falsehood.

Theaet: And properly so.

Soc: And whenever there is present perception corresponding to one of the imprints, but not to another, and the one whose perception is absent is matched with the present perception, in all these cases the mind is deceived.

To sum up, in cases where one does not know, and has never 194B perceived, it seems there is no possibility of deception or false opinion, if what we are saying is in any way sound. But it is in the particular cases where we both know and perceive, that opinion twists and turns and becomes true or false, being true when it directly associates things in line with the proper impressions and imprints, but false when it goes crosswise to the wrong ones.

Theaet: Isn’t that beautifully described, Socrates?

Soc: 194C When you have heard what is coming next you will say so all the more. Indeed forming opinions is beautiful, when they are true, but shameful, when they are false.

Theaet: This must be so.

Soc: Now they say that these differences arise in the following way: when the wax in a person’s soul is deep and plentiful, smooth and evenly wrought, and the perceptions that come in through the senses are impressed upon this waxen heart of the soul, as Homer poetically calls its resemblance to wax,[75] then the impressions generated by 194D the perceptions are clear, and as they have sufficient depth they are enduring, and such people learn easily and then remember, since they do not confuse the imprints from the perceptions, but form opinions that are true. As the imprints are also clear and have abundant space, they quickly assign them to their own individual impressions, that are called things that are, and these people are called wise. Don’t you agree?

Theaet: I couldn’t agree more.

Soc: 194E But when a person’s heart is rugged, a condition praised by the all-wise poet, or when it is sullied or made from impure wax, or is extremely soft or hard, those with soft wax learn readily but are prone to forgetfulness, while the opposite applies to those with hard wax.

Those who have rugged and coarse hearts somewhat stony, with plentiful admixture of earth and filth, retain unclear impressions. And anyone whose wax is hard also retains unclear impressions, as there is no depth in them, while if their wax is soft 195A the impressions quickly become indistinct as they melt into one another. And if besides all this, they are jumbled together, due to the confined space in someone’s tiny little soul, they are even more unclear. All these people are inclined to form false opinions, for whenever they see or hear or think of anything, they are unable to assign it quickly to its proper imprint. Instead, they are slow, and as they assign them incorrectly, they missee, mishear and misconceive most things, and are said, in turn, to be ignorant and deceived about things that are.

Theaet: 195B You are describing these men very accurately, Socrates.

Soc: So should we say that there are false opinions within us?

Theaet: Definitely.

Soc: And true opinions?

Theaet: True also.

Soc: Now, at this stage, do we think we have reached adequate agreement that there really are these two kinds of opinion?

Theaet: Very much so.

Soc: But, Theaetetus, a talkative man is inclined to be truly formidable and disagreeable!

Theaet: Why, what are you talking about?

Soc: 195C I am annoyed about my own stupidity and how truly verbose I am. Indeed what other word could you use for someone who drags discussions this way and that, and cannot be convinced because he is stupid and is hard to tear away from any proposal?

Theaet: Oh, but why are you annoyed?

Soc: Not only am I annoyed, but I am fearful about how I would respond if someone asked: “Socrates, have you really discovered false opinion, that it lies neither in the relation of perceptions to one 195D another nor in the inter-relationship of thoughts, but in the connection between perception and thought?” I think I would agree, priding myself as though we had made a fine discovery.

Theaet: Well, Socrates, I don’t think we need be ashamed of what we have just demonstrated.

Soc: “In that case,” says he: “Does that mean that we shall never believe that a man, whom we only think of but do not see, is a horse, which we neither see nor touch but only think of, though we perceive nothing else about it?” I presume I shall confirm that this is what we mean.

Theaet: And rightly so.

Soc: 195E “Well then”, he continues, “based on this account, one could never believe that the eleven that one merely thinks of are twelve, which again one merely thinks of.” Come on, you give the response this time.

Theaet: Well, I reply that someone who is seeing them or touching them may think that the eleven are twelve, however, he would never form that opinion about the numbers which he holds in mind.

Soc: What about this? Do you think anyone ever considered five 196A and seven within himself, and I don’t mean that he has five men and seven men in front of him or anything like that, I mean just five and seven themselves, which we say have memorial imprints in the wax, and cannot be the subject of false opinion? Now, if someone considered these numbers themselves, talking to himself and asking how much precisely they are, would one person say and believe it is eleven, while another says twelve, or would everyone say and believe that it is twelve?

Theaet: 196B No, by Zeus, there are obviously many who would say eleven; and in the case of larger numbers there are more errors, for I presume you are talking about all numbers.

Soc: Yes, your presumption is correct. Now, consider what is happening in this instance, and whether twelve itself, imprinted on the wax, is believed to be eleven.

Theaet: So it seems.

Soc: Hasn’t our discussion arrived back at the initial proposals?[76] For anyone involved in this error believes that something he knows, is another thing that he also knows; and we said that this is impossible. Indeed this was the very point which forced us to deny that there can be false 196C opinion, lest the same person be constrained to know and not know the same things at the same time.

Theaet: Very true.

Soc: In that case, we must explain the formation of false opinion in some other way than by the misalignment of thought relative to perception. For, if it was this, we would never be deceived in the internal thoughts themselves. But now, either there is actually no false opinion, or it is possible for a person not to know the things which he knows. Which of these options would you choose?

Theaet: You are presenting an impossible choice, Socrates.

Soc: 196D And yet the argument is not going to permit both of them. Nonetheless, should we risk everything and try something audacious?

Theaet: How?

Soc: Let’s decide to state what knowing is actually like.

Theaet: What is so audacious about that?

Soc: You seem not to appreciate that our entire discourse from the beginning has been a search for knowledge on the basis that we do not know what it actually is.

Theaet: I do appreciate this.

Soc: Then does it not seem audacious to be elucidating what knowing is like, without knowing what knowledge is? But in fact, 196E Theaetetus, we have been infected for some time by impure discourse. For we have repeatedly said “we realise” and “we do not realise”, “we know” and “we do not know”, as if we understood one another, though we still did not know about knowledge. Even now, if you don’t mind, at this very moment, we resorted again to “not knowing” and “understanding”, as if it was appropriate for us to use them, when we are actually deprived of knowledge.

Theaet: But how could you conduct discourse at all, Socrates, if you avoided these phrases?

Soc: 197A Well, I couldn’t, being the man I am, unless I was an argumentative fellow, the sort of man who, if he were here now would tell us to avoid these phrases and would rebuke us fiercely for the deficiencies I am referring to. But since we are ordinary folk, would you like me to venture a statement on what knowing is like? It appears to me that this might be of some assistance.

Theaet: Venture away, by Zeus, and you will be generously forgiven if you do not avoid these phrases.

Soc: Well, have you heard what they declare that knowing is these days?

Theaet: I probably have but I cannot recall just now.

Soc: 197B I believe they say that it is “having knowledge”.

Theaet: True.

Soc: Now, we shall change it slightly, and say “the acquisition of knowledge”.

Theaet: But how can you say that this is different from the other wording?

Soc: Perhaps it is not, but when you have heard what I think, then we shall examine it together.

Theaet: Yes, if I am actually able to.

Soc: Well, having does not appear to me to be the same as acquiring. For example, if someone buys a cloak and it is at his disposal but he does not wear it, we would say that he has acquired it but does not have it.[77]

Theaet: Quite right.

Soc: 197C Look now, is it also possible, on this basis, to acquire knowledge and not have it, just as if someone had captured wild birds, pigeons or the like, and provided an aviary at his home and reared them, we would probably say that in a certain sense he always has them because he has acquired them. Is this so?

Theaet: Yes.

Soc: And yet, in another sense, he does not have any of them but he has gained power over them, since he has made them available in an enclosure at home to catch and hold 197D whenever he wishes, capturing the one he wants and releasing it again, and being able to do this as often as he wants.

Theaet: This is so.

Soc: Again, just as we provided the souls with some undefined lump of wax in our previous discussion, we are now building an aviary for a great variety of birds in each soul. Some of these are arranged in flocks and they keep apart from the rest, others form smaller groups, while some birds are solitary and fly as they will among all their fellows.

Theaet: 197E Let the aviary be built. What happens next?

Soc: Well, we should say that while we are infants this structure is empty, and we should appreciate that the birds are things which are known. A person who has acquired knowledge confines it in the enclosure, and we say that he has learned or discovered the matter of which this is the knowledge, and that is what knowing is.

Theaet: So be it.

Soc: 198A Now consider the process whereby we recapture this knowledge whenever we wish, retain it and then let it go again. Consider whether these deserve the same name as the initial acquisition, or a different name. You may understand my meaning more clearly from this example. Is there a subject you call arithmetic?

Theaet: Yes.

Soc: Now, assume that this is a hunt for items of knowledge about all odd or even numbers.

Theaet: I am assuming this.

Soc: And I presume that by means of this subject a man has 198B items of knowledge about number at his disposal and also transmits them to someone else.

Theaet: Yes.

Soc: And we refer to the process of transmission as teaching, the apprehension as learning, and having an acquisition within that aviary as knowing.

Theaet: Yes, certainly.

Soc: Now pay attention to the following. Will the arithmetician who is perfect, have knowledge of all number and nothing less, since he has the details of the knowledge of all numbers in his soul?

Theaet: Of course.

Soc: 198C Well, would a man like this, in mind, ever enumerate anything, either the numbers themselves,[78] or external objects which have number?

Theaet: Of course.

Soc: And we shall propose that enumeration is the process of finding out what the relevant number actually is.

Theaet: It is.

Soc: So we have agreed that this man knows all number, and yet he is trying to find out what he knows, as if he did not know it. Indeed, I presume you are aware of such contradictory statements.

Theaet: Yes, I am.

Soc: 198D Now, when we compared this to the acquisition and hunting of pigeons, we said that the hunt had two aspects. The first is prior to the acquisition for the sake of acquiring something, and then, once acquired, there is capturing and having to hand whatever had previously been acquired. And in this way too, it is possible for a man to learn the same things again, things of which he had previous knowledge, having learned them and known them. Can’t he take up the knowledge of each of them again and retain it, knowledge which he does not have immediately in mind?

Theaet: True.

Soc: 198E This is what I was asking earlier. What terms should be used to describe the arithmetician who sets about calculating, or the grammarian who goes to read something? In such cases, is a person who knows going to learn again for himself, that which he already knows?

Theaet: That would be strange, Socrates.

Soc: But should we say that he is going to read 199A or compute things which he does not know, when we have conceded that he knows all letters and all numbers?

Theaet: No, that too is illogical.

Soc: Well, would you like us to say that we do not care about names, and that someone can drag knowing and learning wherever they please? But since we have defined the acquisition of knowledge as one thing, and having it as another, it is impossible for someone not to have acquired that which he has acquired, and consequently, it never happens that someone does not know that which he knows. However, we do say that it is possible 199B to pick up a false opinion about it, for it is possible not to hold the knowledge of that but another knowledge instead. This happens when someone is on the hunt for an item of knowledge which is flying about the aviary, but mistakenly grabs a different one instead of the one he wanted. So in the case where he thought that the eleven was twelve, he had caught, within himself, the knowledge of the eleven rather than the twelve, like catching a dove instead of a pigeon.

Theaet: Yes, that makes sense.

Soc: But, whenever he catches what he is trying to catch, he is unerring and he thinks things that are; and so, in this way, there can be both true and 199C false opinion, and the issues which troubled us earlier[79] no longer present an obstacle. Perhaps you will agree with me, or will you take a different approach?

Theaet: I take this approach.

Soc: Well then, we are rid of the issue of people not knowing things that they know, for it can never turn out that we have not acquired the things we have acquired, whether we are deceived about something or not.[80] But it seems to me that another more formidable issue is looming.

Theaet: What sort of issue?

Soc: Whether the interchange of pieces of knowledge will ever give rise to false opinion.

Theaet: How so?

Soc: 199D The first concern is that someone who has knowledge of something is ignorant of that very thing, not on account of ignorance, but on account of his own knowledge. Then comes the statement that he thinks that this thing is something different, and the different thing is this thing. Is it not very unreasonable that when knowledge is present, the soul knows nothing and is utterly ignorant? Based on this account, why couldn’t the presence of ignorance enable us to know something, or blindness make us see, if knowledge ever really does make someone ignorant?

Theaet: 199E Well, Socrates, perhaps we went wrong when we proposed that these birds stand only for items of knowledge, and we should also propose that there are ignorances flying around in the soul at the same time, and the seeker sometimes gets hold of knowledge and sometimes of ignorance concerning the same thing. He then forms false opinions on account of the ignorance and true opinions on account of the knowledge.

Soc: I can hardly refrain from praising you, Theaetetus; however, you should examine what you have said once more. Now, let it be as you say, that someone who gets hold of ignorance 200A will form false opinions, according to you. Is that so?

Theaet: Yes.

Soc: Of course, he will not think that he is forming false opinions.

Theaet: How could he?

Soc: Indeed he will think they are actually true, and he will adopt the stance of a man who knows on matters where he is in error.

Theaet: Yes, he will.

Soc: So he will believe he is in possession of knowledge, not ignorance, because that’s what he has hunted down.

Theaet: Obviously.

Soc: Well, we are back again at our initial problem, after a very circuitous diversion. Indeed that disputatious man[81] will laugh 200B and say “How does this work, my good fellows, does someone who knows both, believe that some item of knowledge which he knows, is some ignorance which he also knows? Or, does he know neither of them, and think that one, which he does not know, is another which he does not know? Or, having known one, and not the other, does he believe that the one he knows, is the one he does not know, or that the one he does not know, is the one he does know?

Or again, will you go on to say that there are additional knowledges about the items of knowledge and the ignorances, and that he acquires these knowledges and keeps them 200C in some other ridiculous aviaries, or in wax imprints? Does he know these as long as he possesses them, though he may not have them immediately at his disposal, in his soul? Well, are you going to be compelled to go through this same cycle indefinitely without getting anywhere?” How shall we respond to these questions, Theaetetus?

Theaet: By Zeus, Socrates, I don’t know what we should say.

Soc: So in that case, my boy, was the argument right to rebuke us and show that we were wrong to set knowledge aside and 200D seek false opinion first? Something which it is impossible to understand until we have a proper grasp of what knowledge actually is.

Theaet: As things stand, Socrates, we must believe what you are saying.

Soc: So what are we to say that knowledge is, for I presume we are not going to give up yet?

Theaet: Far from it, unless you yourself have had enough.

Soc: Tell me then, what definite statement can we make, that involves us in the least self-contradiction?

Theaet: 200E The very proposition we tried before. In fact, it is the only one I have.

Soc: What is it?

Theaet: That knowledge is true opinion: forming true opinions is, after all, a process which is supposedly free from error, and whatever arises on this basis is entirely noble and good.

Soc: The guide by the river bank says: “You’ll be shown the depth”, and, in this case, once we proceed with our search perhaps something which turns up along the way 201A may reveal what we are seeking, but if we wait, nothing will become clear.

Theaet: You’re right, so let’s go ahead and consider this.

Soc: Well, this will be a brief investigation, for there is a whole profession pointing out to you that true opinion is not knowledge.

Theaet: How is that? What profession?

Soc: The profession of the wisest men of all, whom we call orators and advocates. For these men use their skill to persuade rather than teach, and they make people form the opinions they want them to form. Or do you believe that there are teachers so clever,201B that they can adequately teach the truth about what happened to people whose money was stolen, or who were otherwise assaulted, to people who were not present? Can they do this in the little time allowed by the water-clock in the court?

Theaet: I don’t believe that they can teach them at all, but they may persuade them.

Soc: And don’t you say that persuading them is making them form an opinion?

Theaet: Of course.

Soc: Now, when a jury is justly persuaded about matters that only an eyewitness, and no one else, could know, on that occasion they are judging from hearsay. 201C They have caught hold of a true opinion, but haven’t they judged without knowledge, having been persuaded of what is right, if their adjudication is actually sound?

Theaet: Entirely so.

Soc: But, my friend, if knowledge and true opinion are really the same, the best of jurors could never form a correct opinion in the absence of knowledge. So in that case, it seems they are different from one another.

Theaet: Oh, Socrates, I had forgotten something that I once heard someone saying, but I remember now: he said that true opinion 201D along with an account is knowledge, while in the absence of an account it is outside the realm of knowledge. And whatever is without an account is not knowable, yes, that’s the very term he used, while anything that has an account is knowable.

Soc: Well said, but now explain how he distinguished the knowable things from the unknowable, for I may have heard the same things you have heard.

Theaet: Well, I don’t know if I can work that out; however, if someone else were to explain it, I think that I could follow.

Soc: Then listen to a dream in return for a dream, for I too 201E imagined that I heard, from some people, that the primary so-called elements, from which we and all else are compounded, lack any account, as each, just by itself, may only be named. Nothing else can be said of it, either that it is, or that it is not, for in that case we would be assigning being or non-being to it, 202A but we must apply nothing if we are to speak of itself alone. So we should not apply “it” or “that” or “each” or “only” or “this” or the numerous other terms like them, for these are in circulation and are applied generally, being different from whatever they are assigned to. But if it were possible to describe an element and it had its own particular account, it would have to be described without all of the others. But as things stand,202B it is impossible for any of the primals to be expressed in an account; for they can only be named, as name is all they have. But when things are compounded from the primals, their names are woven together, just as they themselves are woven, and they generate an account, for the essence of an account is an interweaving of names. Thus, the elements have no account and are unknowable, and yet they are perceivable, while the compounds are knowable and describable and can be the object of true opinion. Now, whenever someone has acquired a true opinion 202C of something, without an account, then his soul has arrived at the truth about it, but does not know it; for a man who can neither give nor receive an account of a thing, is ignorant about it. But once he has acquired an account, all these other things can happen, and he is perfected in knowledge. Was your dream like that or was it different?

Theaet: It was exactly like that.

Soc: Are you satisfied then, and are you proposing that true opinion with an account is knowledge?

Theaet: Quite so.

Soc: 202D Well, Theaetetus, have we really captured something this very day, that generations of wise men have sought, and grown old without finding?

Theaet: Socrates, I really believe that what we have just said is an excellent description.

Soc: And that is quite likely so, for what knowledge could there be in the absence of an account and true opinion? However, there is one thing we said which is bothering me.

Theaet: What is it?

Soc: What seems like the cleverest statement of all; that the elements 202E are unknowable, while the class of compounds is knowable.[82]

Theaet: What’s wrong with that?

Soc: Well, we need to know, for we are holding the patterns of the argument like hostages, patterns used by the person who said all this.

Theaet: What patterns?

Soc: The elements and syllables of writing, or do you imagine that the person who said all we are recounting had something else in view?

Theaet: No, only these.

Soc: 203A Now let us test them, and let us test ourselves in particular, as to whether we learned writing on this basis or not. Well, in the first place, do the syllables have an account while the letters do not?

Theaet: Perhaps.

Soc: That is certainly how it seems to me. If someone were to ask about the first syllable of “Socrates” and said “Theaetetus, what is SO?” how would you respond?

Theaet: That it is S and O.[83]

Soc: And isn’t that your account of the syllable?

Theaet: It is.

Soc: 203B Very well, now give an account of S in the same way.

Theaet: But how could anyone speak of the letters of a letter? Actually, Socrates, the S is one of the voiceless letters: it is just a sound like a hissing of the tongue; while B, for its part, has neither sound nor voice, nor have most of the letters. So it is quite appropriate to say they have no account, when even the clearest of them, the seven vowels, have a voice alone, but no account at all.[84]

Soc: So, my friend, we have come to this conclusion about knowledge.

Theaet: It appears that we have.

Soc: 203C But what about this? Have we really shown that the elements are unknowable, though the syllables are knowable?

Theaet: Quite likely.

Soc: Well then, are we saying that the syllable is both letters, or all of them if there are more than two, or is it a single form which arises from putting them together?

Theaet: I presume we are referring to all of them.

Soc: Then consider two, the S and the O. This pair is the first syllable of my name. Can someone who knows the syllable avoid knowing both letters?

Theaet: 203D Of course not.

Soc: So he knows the S and the O.

Theaet: Yes.

Soc: Yes, but does he know both without knowing one or the other?

Theaet: No, that would be bizarre and illogical, Socrates.

Soc: However, if it really is necessary for someone to know each letter if he is to know both, then anyone who is ever going to know the syllable absolutely must have prior knowledge of the letters. On this basis, our nice proposition has taken to its heels and fled.

Theaet: 203E And very suddenly too!

Soc: Yes, we are not being careful enough with it. Perhaps we should be proposing that the syllable is not the letters, but a single entity arising from them, having a single form of its own that is different from the letters.

Theaet: Yes indeed, and that is probably a better suggestion than the other one.

Soc: We should consider this, and not give up like cowards on a significant and serious proposition.

Theaet: We should not.

Soc: 204A Then let our present statement stand: that a syllable is a single form which arises from joining the individual elements together, such as occurs in writing and in all other situations.

Theaet: Yes, certainly.

Soc: Therefore, it must not have parts.

Theaet: Why is that?

Soc: Because the whole must be all the parts of anything which has parts, or do you also say that the whole is a single entity that arises from the parts, and is different from all the parts?

Theaet: I do.

Soc: But do you refer to the entire and the whole as different from 204B one another or the same?

Theaet: I am not clear about that but because you are asking me to respond, eagerly, I’ll take a chance and say that they are different.

Soc: Well, Theaetetus, you have the promptness right, but we should consider whether the answer is right.

Theaet: Yes, we must do that.

Soc: Wouldn’t the whole be different from the entire, according to the current proposition?

Theaet: Yes.

Soc: What about this? Is there any difference between the entire and them all? For instance, when we say one, two, three, four, five, six, or twice three, 204C or thrice two, or four plus two, or three plus two plus one, are we talking about the same thing or something different in all such cases?

Theaet: The same.

Soc: And is that different from six?

Theaet: No.

Soc: Then with each statement haven’t we referred to all six?

Theaet: Yes.

Soc: But if we say the entire, aren’t we referring again to one thing?

Theaet: We must be.

Soc: And is that a different thing from the six?

Theaet: No.

Soc: 204D So in any cases involving number, do we refer to the entire and, “them all”, as the same?

Theaet: It appears so.

Soc: Then let’s talk about them as follows: the number of a mile and a mile are the same, aren’t they?

Theaet: Yes.

Soc: This also applies to the number of a furlong.

Theaet: Yes.

Soc: Similarly in the case of an army and the number of an army, and everything of that kind, the entire number is what each of them, entirely, is.

Theaet: Yes.

Soc: 204E But is the number of each, anything other than the parts?

Theaet: Nothing other.

Soc: And does anything which has parts, consist of parts?

Theaet: It appears so.

Soc: But we did agree that all the parts are the entire, if in fact the entire number is also the entire.

Theaet: So we did.

Soc: Then the whole does not consist of parts; for if it were all the parts, the whole would be the entire.

Theaet: So it seems.

Soc: But is a part, as such, part of anything other than a whole?

Theaet: Yes, of the entire.

Soc: 205A Well, you are putting up a brave fight, Theaetetus, but isn’t the entire actually entire whenever there is nothing missing?

Theaet: Necessarily.

Soc: But won’t that same thing be a whole, as nothing is missing from it? And that from which something is missing is neither whole nor entire, for the same cause produces the same effect in both.

Theaet: It seems to me now that there is no difference between whole and entire.

Soc: Were we not saying that for anything with parts, the whole and also the entire will be all the parts?[85]

Theaet: Yes, indeed.

Soc: Now, returning to my previous inquiry, if the 205B syllable is not the letters, it must not have the letters as parts of itself,[86] or else it will be the same as them and be just as knowable as they are. Is that it?

Theaet: That’s it.

Soc: And to prevent this from happening, didn’t we propose that it was different from the letters?

Theaet: Yes.

Soc: Well then, if the letters are not parts of the syllable, can you propose other candidates that are part of the syllable, without, however, being the letters of the syllable?

Theaet: Certainly not, Socrates, for if I were to agree that it has some parts, it would be a bit ridiculous to ignore the letters and look for other candidates.

Soc: 205C Yes, entirely so, Theaetetus, based upon the current proposition a syllable would be a single indivisible form.

Theaet: So it seems.

Soc: Now, my friend, do you remember a little while ago we accepted what we regarded as a sound proposal, that there is no account of the primals from which all else is compounded because each of them, just by itself, is uncompounded, and neither the terms “is” nor “this” can properly be applied to them as they describe different and distinct things, and this is the reason why a primal is indescribable and unknowable?

Theaet: I remember.

Soc: 205D Well, is this the reason why it is uniform and indivisible, or is there another? Indeed I can discern no other.

Theaet: No, it appears that there is no other.

Soc: Doesn’t the compound fall into the same category as the element, if in fact it has no parts and is one form?

Theaet: Entirely so.

Soc: So then, if the compound is many elements, and is a whole with the elements as its parts, the compounds will be just as knowable and expressible as the elements since the many parts have turned out to be the same as the whole.

Theaet: 205E Certainly.

Soc: But if, on the other hand, the compound is one and partless, the compound, like the element, will be just as indescribable and unknowable, for the same reason; the unity and indivisibility will make them so.

Theaet: I cannot disagree with you.

Soc: So we should not accept it when someone says that the compound is knowable and expressible while the element is not.

Theaet: No, indeed not, if we are persuaded by this argument.

Soc: 206A Well then, would it be better to agree with someone who says the opposite, because of what you yourself discern in the process of learning to write?

Theaet: What do I discern?

Soc: In learning to write, you have achieved no more than the ability to recognise each letter, just by itself, with your eyes and ears, so that its position in speech or writing does not confuse you.

Theaet: What you say is very true.

Soc: And isn’t the perfectly trained lyre player able 206B to follow each note, and say what string it came from? Of course, everyone would agree that these notes are the letters of music.

Theaet: They would.

Soc: Now, if we had to generalise to others, from the letters and syllables within our own experience, we would say that having knowledge of the elemental category is much more critical and important in the complete apprehension of each subject than knowledge of the compound. And if anyone says that the compound is knowable, while the element is by nature unknowable, we shall assume that he is joking, either deliberately or unwittingly.

Theaet: We certainly will.

Soc: 206C Now, I think even more proofs of this may turn up, but we must not forget the current issue because of them. We want to see what is meant by the statement that the most complete knowledge arises from the addition of an account to true opinion.

Theaet: Yes, we need to see that.

Soc: Come then, what exactly are we supposed to understand by “an account”? For it seems to me to mean one of three things.

Theaet: What are they?

Soc: 206D The first would involve making one’s thoughts manifest in sound, using verbs and nouns, forming the opinion into an image in the stream issuing from the mouth, just like an image in a mirror or in water. Or don’t you think that an account is something of that sort?

Theaet: I do. Anyway, we do say that a person who is doing this is giving an account.

Soc: What’s more, this can actually be done quite easily by everybody, so anyone who is not born deaf and dumb can explain what they think about every issue. This being the case, anyone who forms a right opinion 206E will turn out to have that opinion with an account and right opinion without knowledge will never arise at all.

Theaet: True.

Soc: Well, we should not be too quick to accuse the person who made the statement about knowledge which we are now considering of talking nonsense, for perhaps he did not mean this, but the ability to give an answer in terms of the elements 207A when asked what anything is.

Theaet: Can you give an example, Socrates?

Soc: Yes, it is like Hesiod referring to “the one hundred wooden parts of a wagon”.[87] Now, I could not say what they are, nor I imagine could you, but if we were asked what a wagon is, we would be satisfied if we could say “wheels, an axle, body, rails and yoke”.

Theaet: Yes, certainly.

Soc: And yet, he might think we were ridiculous, just as if we 207B responded based upon the syllables when asked what your name was. Ridiculous because, although what we said was correctly conceived and expressed, we thought we were grammarians who had a grammatical account of Theaetetus’ name and were expressing it. Whereas it is not possible to give a knowledgeable account of anything until you can describe that by means of the elements combined with true opinion, as I think we said before.

Theaet: Yes, we said that.

Soc: Now, he will accept that while we really do have true opinion about the wagon in this way, someone who is able to describe its being 207C by means of those one hundred parts, once he has also attained this, has added an account to the true opinion, and becomes expert and knowledgeable about the being of the wagon, rather than merely opinionated, as he has described the whole by means of the elements.

Theaet: Don’t you think this is sound, Socrates?

Soc: Tell me whether you think so, my friend, and whether you accept that a description of anything based upon the elements is an account, while it is not an account if it is based on compounds or larger units, tell me 207D so that we can consider it.

Theaet: Yes, I certainly accept this.

Soc: And do you regard anyone as knowledgeable about something when he thinks that the same element is part of one entity at one moment and part of a different entity the next, or when he thinks one element and then a different element belongs to the same entity?

Theaet: By Zeus, I do not.

Soc: Then are you forgetting that this is what you and the other boys did, when you began learning to read and write?

Theaet: Do you mean that we first believed that one 207E letter, then a different letter, belonged to the same syllable, or we placed the same letter sometimes in the appropriate syllable and at other times in a different one?

Soc: That is what I mean.

Theaet: By Zeus, I certainly have not forgotten, nor do I regard people as knowledgeable when they are at that stage.

Soc: 208A What about a situation where someone is writing “Theaetetus” and writes “TH” and “E” because he thinks he should, but when he goes on to try to write “Theodorus” he writes “T” and “E” because he thinks he should?[88] Shall we say that this fellow knows the first syllable of both your names?

Theaet: No, we have already agreed that when a person is at that stage he does not yet know.

Soc: And could he be in a similar predicament about the second syllable, and the third, and the fourth?

Theaet: There is no reason why not.

Soc: Therefore, when he has a description based on the letters, he will write “Theaetetus” with right opinion, once he writes it in the proper sequence.

Theaet: Obviously.

Soc: 208B Isn’t he still devoid of knowledge, though he is forming a right opinion according to us?

Theaet: Yes.

Soc: Yet he has an account along with right opinion, for he was writing using an approach by means of the elements, and we agreed that this constitutes an account.

Theaet: True.

Soc: So, my friend, here we have right opinion combined with an account that should not yet be called knowledge.

Theaet: I’m afraid so.

Soc: Well, it seems our wealth was but a dream when we imagined we had a perfectly true account of knowledge. But are we condemning 208C it too soon? Perhaps an account should not be defined like this, for there were three options available to a person who defines knowledge as right opinion together with an account, and the last of the three still remains.

Theaet: You are right to remind me, yes, there is one remaining option. The first was an image of thought expressed in speech; the one we have just discussed was the approach to the entire based upon the elements; now, what do you say the third option is?

Soc: Exactly what most people would say it is: being able to express some mark by which the item in question is distinguished from everything else.

Theaet: Can you give me an example of an account of something?

Soc: 208D If you wish. For instance, the statement that the sun is the brightest of the heavenly bodies moving round the earth, would, I believe, be quite acceptable to you.

Theaet: Yes, certainly.

Soc: Now, understand why such a statement is made, and in fact, we have just given the reason. Once you understand the distinguishing characteristic by which something is distinguished from others, you will, some say, have obtained an account of it. But as long as you apprehend some common feature, your account will relate to whatever entities have this in common.

Theaet: 208E I understand, and I think it is appropriate to refer to this sort of thing as an account.

Soc: Once someone with right opinion about any one of the things that are, also grasps its distinction from the others, he will become knowledgeable about that of which he was previously just opinionated.

Theaet: So we say anyway.

Soc: Well now, Theaetetus, since I have come closer to this statement, I understand it even less. It’s like those shadow-drawings, which only seem to make sense as long as you stand far away from them.[89]

Theaet: What do you mean?

Soc: 209A I shall tell you if I can. I have right opinion about you, and if I also obtain an account of you I shall actually know you, but otherwise I shall only be forming opinions.

Theaet: Yes.

Soc: But the account is an explanation of your distinctiveness.

Theaet: So it is.

Soc: Therefore, while I was only forming opinions, I had no mental grasp of anything at all by which you are distinguished from others.

Theaet: Apparently not.

Soc: So I had some common qualities in mind that you as well as anyone else possess.

Theaet: 209B So you must.

Soc: Come, by Zeus, in that case how did I ever form an opinion about you rather than anyone else? For I suppose I am thinking that this is Theaetetus, who is human and has a nose, eyes and mouth, and so on for each of the organs. Will these ideas themselves enable me to think of Theaetetus rather than Theodorus, or any so called outer barbarian?

Theaet: How could they?

Soc: However, if I do not think only of people with a nose and eyes, 209C but of those with a snub-nose and protruding eyes, won’t I form an opinion, in that case, which applies to you as much as to myself or anyone else like us?

Theaet: Yes.

Soc: In fact, Theaetetus will register no opinion within me until this snub-noseness forms a distinct record imprinted within me, which is different from the record of any other snub-noseness which I have seen. The same goes for your other characteristics, and this imprint will act as a reminder, if I meet you tomorrow, and will enable me to form a correct opinion about you.

Theaet: Very true.

Soc: 209D So in each case, the right opinion also involves distinctiveness.

Theaet: So it appears.

Soc: In that case what more can the account add to right opinion? For if you say it adds an opinion by which something is distinguished from the others, then, the process becomes quite ridiculous.

Theaet: How?

Soc: When we have right opinion of things, by which they are distinguished from the others, we are asked to add another right opinion of the same things, by which they will differ from the others. So the circuitousness of a roller or a pestle or anything 209E like that would be nothing in comparison to this process which may properly be called the directions of a blind man. Indeed asking us to acquire what we already have so that we may understand the things about which we form opinions, is really and truly a deed of darkness.

Theaet: Is there another option? What else were you going to suggest a moment ago?

Soc: Well, my boy, if adding an account means knowing the distinctiveness, rather than having an opinion about it, our most perfect account of knowledge would be an oddity. For knowing 210A presumably means acquiring knowledge, doesn’t it?

Theaet: Yes.

Soc: Therefore, it seems that when asked what knowledge is, this account replies that it is right opinion along with knowledge of distinctiveness, for that is what acquisition of an account is according to this.

Theaet: So it seems.

Soc: And it is really quite simple minded, when we are in search of knowledge, to say that it is right opinion along with knowledge, be it of distinctiveness or anything at all. 210B So, Theaetetus, knowledge turns out to be neither perception, nor true opinion, nor an account along with true opinion.

Theaet: It seems not.

Soc: Well then, my friend, are we still pregnant or in labour in relation to knowledge, or have we brought forth all there is?

Theaet: Oh yes, by Zeus, because of you I have spoken more than I had within myself.

Soc: Isn’t our art of midwifery saying that all these are wind-eggs and not worth rearing?

Theaet: Most emphatically.

Soc: Well, Theaetetus, if you attempt to conceive 210C other thoughts in future, if you do conceive, you will be filled with better thoughts because of our present enquiry. But should you remain barren, you will be less oppressive to your associates, and gentler, as you will refrain, wisely, from thinking that you know what you do not know. This is as much as my skill can accomplish, it can do no more, and I know nothing that is known by the great and wonderful men of the past or the present. 210D This midwifery has been allotted to me and my mother by god, she for women and I for the young and noble, and all who are good.

Now, I must go to the Stoa Basileios to answer the charge which Meletus has laid against me.[90] But in the morning, Theodorus, let us meet here again.


1 Eucleides, 450-380, was the founder of the Megarian School of philosophy. Terpsion was also from Megara, nothing more is known. Eucleides and Terpsion are mentioned in the Phaedo as being among those present at the death of Socrates. Theodorus and Theaetetus were mathematicians and geometers. Both are present in the Sophist and Thedorus in the Statesman as well. Theodorus, from Cyrene in North Africa, lived at the end of the 5th century. He was the teacher of Theaetetus, a gifted Athenian, 415-391, who died after being wounded in battle. All dates are approximate throughout and are BCE.

[2] The commercial and civic centre of Athens and a gathering place.

[3] Theaetetus was mortally wounded (spring 391) in the war between Athens and her allies and Sparta, fought mostly on Corinthian territory.

[4] Socrates was put to death in spring 399 which gives the dramatic date for this dialogue. See 210D.

[5] A settlement near the Cephisus River west of Athens, so quite a long walk.

[6] The opening scene takes place in Eucleides house in Megara and the meeting of Socrates, Theodorus and Theaetetus in a gymnasium in Athens 8 years earlier.

[7] The southern most part of Attica, i.e. the territory belonging to Athens.

[8]The Greek word is arete. It is translated as excellence.

[9] Wiser here implies more expert.

[10] This refers to Socrates the Younger, who in later life was a member of Plato’s Academy, one of Theaetetus’ companions mentioned at 144C.

[11] A flat number is a square whose area is equal to the number and so the side of the square, here called the line, is equal to the square root of the number. So in the examples given, 3 as a flat number has a common measure with 4, but the side of the flat number 3 is √3 while the side of the flat number 4 is 2 and they have no common measure since √3 cannot be expressed as a fraction so as to yield a simple numerical ratio of 2. We use the term irrational to describe √3 but the entire process here is being described geometrically rather than arithmetically, and the lack of a common measure, called incommensurability, captures the essence of the problem. Contrast 4 and 9 where the sides (of the square) or magnitudes are 2 and 3 and so they have a common measure and relate as 2/3 as also do 16 and 36: √16=4, √36=6 4:6 −> 2:3. However, this process will not work with, for example, 15 and 36.

[12] Burnyeat points out that this name means ‘She who brings virtue to light’.

[13] Artemis, sister of Apollo, was the goddess of hunting and of women, particularly at the time of childbirth. As Mistress of the Animals, she was the goddess of all wild nature and protectress of all young living things.

[14] Socrates may be referring to Apollo. However Plato used god and gods interchangeably and often did not specify which god.

[15] Aristeides II, 440’s-411, grandson of a famous Athenian military and political leader of the same name. At the end of the Laches Socrates says he will undertake to educate the young man.

[16] In the Phaedrus (242b-c) Socrates describes his daimon as “the usual sign that comes to me and always holds me back from something I am about to do.” See also Apology for references.

[17] Prodicus, a contemporary of Socrates, from Ceos, was a distinguished sophist who taught semantics and rhetoric, well-respected by Athenians of his day. He is portrayed in Plato’s Protagoras.

[18] See 148c where Theaetetus describes his state.

[19] See 144A for Theodorus’ praise of Theaetetus’ fine qualities.

[20] An unproductive or imperfect egg, especially one with a soft shell.

[21] Protagoras, 490-420, was a renowned sophist. He taught rhetoric and virtue and wrote several books.

[22] Parmenides, born 515, was a philosopher from Elea in Italy. Heracleitus for whom all things were in permanent tension was from Ephesos in Ionia (western coast of modern-day Turkey) and Empedocles was from Sicily, for him the elemental things that are, included Love and Strife alongside fire, air, water, and earth. Epicharmus was an early 5th century comic poet from Syracuse in Sicily. Homer was a bard and epic poet in the 8th century who composed the Iliad and the Odyssey.

[23] Iliad viii, 17-27 where Zeus says he could bind everything in a golden cord and tether it to Mount Olympus, leaving it to hang in mid-air.

[24] About the dice.

[25] The reference is to Euripides, Hippolytus line 612. Hippolytus says of an oath he has made but not kept: “my tongue has sworn, but my mind is unsworn.”

[26] The Cratylus connects Iris with εἴρειν (408b), and εἴρειν’ (λέγειν) with dialectic (398d). So Iris (philosophy) is daughter of Thaumas (wonder). Since our passage is unintelligible without the Cratylus, the Theaetetus must be the later of the two. Cornford, p. 43.

[27] See 152D.

[28] See 151D-152A.

[29] This is basically Protagoras’ statement, 152A, with the addition of “for me”.

[30] See footnote 23.

[31] After the fifth day of the birth of a baby, it was carried round the family hearth, thereby symbolically introducing it to the household gods and placing it under their protection.

[32] Truth was apparently the title, or part of the title, of Protagoras’ book.

[33] See 152A for what Protagoras says.

[34] Sparta, a militarised society, renowned for an austere public upbringing which included athletic training.

[35] This is a reference to Protagoras’ statement: ‘Concerning gods I am unable to know whether they exist or do not exist, or what they are like in appearance; for there are many hindrances to knowledge, the obscurity of the subject and the brevity of human life’.

[36] Socrates here summarizes 163D-164B.

[37] Callias III, 450-367, son of the richest man in Greece. He was a student of Protagoras, Prodicus and Hippias. Plato’s Protagoras takes place in his house where the visiting sophists are staying.

[38] The “debater” is here compared to a peltast, a lightly armed mercenary infantryman, usually carrying a javelin, who was particularly useful in skirmishes or as an advanced guard.

[39] This is a reference to Socrates’ comment at 161C. Proverbially the pig lacked culture and finer perception; his short comings were intellectual as much as social and moral.

[40] See 159B-E

[41] The Greek word sophistes, is related to sophos meaning wise, skilled, clever, hence a sophist is one who professes to be wise. The sophists offered exhibitions, sample lectures or set speeches used to show off their skill.

[42] See 166A.

[43] Sciron, a brigand on the coastal road at the Isthmus of Corinth, kicked travellers off the cliffs into the sea where they were eaten by a giant turtle. The hero Theseus, on his way to Athens, dispatched him in the same way.

[44] Antaeus, a giant, forced all passers-by to wrestle with him. He drew his invincible strength from the earth but was finally defeated by Heracles who lifted him in the air and then crushed him to death.

[45] Heracles, the greatest Greek hero, and Theseus, the greatest Athenian hero, both pre-Trojan War, had parallel careers in that they had to perform a series of labours. Although great protectors and saviours, they were also flawed.

[46] The concession referred to occurs at 166e-167b where Socrates, speaking as Protagoras, asserts that wise men can change the opinions of others to produce better opinions but they are not any truer.

[47] Homer, Odyssey xvi.121 refers to the number of enemies Odysseus faces on his return.

[48]See 161B, 169D, the “greater discussion” emerges at 172C.

[49] In law courts and elsewhere speeches were timed by means of a water clock (klepsydra). Water flowed from one vessel to another and measured out the desire amount of time.

[50] This refers to a written statement presented by each party before the trial and subsequently confirmed by an oath.

[51] Pindar was a lyric poet from Boeotia, 518-438, who composed victory odes for athletes. Quoted verse possibly from a lost poem.

[52] Thales from Miletus in Ionia predicted the eclipse dated 585, was an engineer, geometer and astronomer and the most scientific of the Seven Sages listed by Plato and Pausanias (2nd AD).

[53]Hellas was the territory occupied by Hellenes, a name they still call themselves. Barbarian refers to all non-Greeks.

[54]See 166c-168c

[55] See 171B-C.

[56] See 151D-E.

[57] See footnote 23.

[58] This is the principle that everything is really motion (156A).

[59] The inhabitants of Heracleitus’ home city of Ephesus.

[60] See 152E.

[61] From Parmenides: see Cornford, p. 94.

[62] Melissus from island of Samos off the coast of Ionia, was a pre-Socratic philosopher in the tradition of Parmenides that saw reality as unchanging and single, 5th century.

[63] See 156A-157C

[64] See 156A-157C

[65] Iliad, iii, 172; Odyssey, viii.22; xiv, 234.

[66] This encounter, fact or fiction, is described in Plato’s Parmenides.

[67] The Greeks concealed themselves inside an enormous wooden horse which was rolled inside the walls of Troy. In the dead of night, they poured out into the city and destroyed it and its inhabitants.

[68] See 143E.

[69] See 167b, 170a-172b.

[70] Socrates has avoided Parmenidean ideas 183E-184B.

[71] Mnemosyne, Memory, was the mother of the nine Muses, and Zeus the father.

[72] As these cannot be known they are either unperceived and unknown or if perceived they are ‘only perceived’ as they cannot be known also.

[73] See 192A.

[74] Aeschylus, The Libation Bearers, line 197. Electra recognizes the presence of her brother from the likeness of his footprint to her own.

[75] The Homeric word for heart is “kear” or “ker” which superficially resembles the word for wax “keros”.

[76] See 188a-c.

[77] The Greek verb for “I have” can mean not only “I possess, but also “I have it on” (e.g. an article of clothing) or “I have hold of it.”

[78] See 196a.

[79] See 196a.

[80] The argument is that the person knows because he has acquired the knowledge (bird) but when he goes to catch it he picks up the wrong item of knowledge, and yet he still knows as knowing equals acquisition.

[81] See 195c-e.

[82] The Greek word for element and letter is the same. The initial reference here is to a response based upon syllables rather than letters or elements.

[83] Theaetetus actually says, ‘That it’s sigma and omega’, using the names of the Greek letters in Socrates’ name.

[84] The ‘seven’ are the seven vowels of ancient Greek, as contrasted with two classes of consonant: mutes like B, which cannot be pronounced without a vowel, and semivowels like S, which can.

[85] See 204a.

[86] See 203e.

[87]Hesiod, 8th century, was paired with Homer as the second great Greek epic poet. He composed Theogony and Works and Days. The quote is from Works and Days, 456.

[88] Socrates actually says ‘he thinks he should write theta and epsilon’. Using the names of the Greek letters in the first syllable of Theaetetus’ name. There are only two such letters because Greek represents the sound TH by the single letter theta. Moreover, this sound was a plosive (as in English fathead), rather than a fricative (as in English thin), and so easy enough to confuse with TE.

[89] The technique (skiagraphia “shadow-painting”) depended on contrasts between light and shade to create the appearance of form and volume.

[90] The Stoa Basileios (Royal Stoa) housed the office of Athens’ chief religious officer. Here Meletus made his formal accusation of impiety in front of the King Archon.