Theaetetus

EuclidesJust in from the country, Terpsion, or have you been back a while?note

TerpsionA good while. And I was looking for you in the marketplace, and wondering why I couldn’t find you.

EuclidesWell, I wasn’t in town.

TerpsionWhere were you, then?

EuclidesI was going down to the harbor, and I ran into Theaetetus being carried from the army camp at Corinth to Athens.note

TerpsionAlive or dead?

EuclidesAlive, but only just. He’s in a bad way from some wounds, but what’s really getting the better of him is the sickness that’s broken out in the army.

TerpsionNot dysentery?

EuclidesYes.

TerpsionWhat a man you’re telling me is in danger!

EuclidesA fine and good man, Terpsion. Why, just now I was listening to some people singing his praises for the way he fought in the battle.

TerpsionNothing strange in that. It would be far more surprising if 142c he weren’t like that. But why didn’t he stop over here in Megara?

EuclidesHe was in a hurry to get home. I certainly begged him to stay and urged him to, but he wouldn’t. So I saw him off, and as I was walking back I remembered, with amazement, how prophetically Socrates had spoken, about this among other things. I think he met Theaetetus shortly before his death, when Theaetetus was still a boy, and after spending time with him and talking with him he greatly admired his nature. And when I went to Athens he told me in detail the conversation he’d had 142d with him, which was very well worth hearing, and he said that it was absolutely inevitable that this boy would become distinguished, if he lived to grow up.

TerpsionAnd it seems he spoke the truth. But what was the conversation? Could you tell it to me?

EuclidesGood heavens, no, not just like that, from memory. 143a But as soon as I got home back then, I wrote down notes, and later I wrote it out at leisure as I recalled it, and whenever I went to Athens I would ask Socrates again about whatever I hadn’t remembered, and when I got back here I would make corrections. So I have pretty much the whole conversation written down.

TerpsionThat’s true. I’ve heard you say so before, and I’ve always meant to ask you to show it to me, but I’ve kept putting it off until now. But what’s to stop us going through it now? I certainly need a rest anyway, since I’ve come in from the country.

EuclidesWell, I myself saw Theaetetus off as far as Erineum, so I wouldn’t mind a rest either. Let’s go, and while we rest, the boy will read it to us.note

TerpsionGood idea.

EuclidesHere’s the book, Terpsion. Now, this is how I wrote the conversation down: not with Socrates narrating it to me, the way he narrated it, but talking with the people he said he talked with. He said they were Theodorus the geometer and Theaetetus. So that in the 143c writing the bits of narration between the speeches wouldn’t be a nuisance—where Socrates says of himself, for example, “and I said” or “and I remarked,” or of the person answering, “he agreed” or “he didn’t accept that”—for that reason I wrote it as though he were talking directly with them, and cut out that sort of thing.note

TerpsionAnd that’s perfectly reasonable, Euclides.

EuclidesBoy, take the book and read.

SocratesIf I cared more about things in Cyrene, Theodorus, I’d be asking you about things there and about the people there—whether any of the young men there are applying themselves to geometry or any other kind of philosophy. As it is, I love them less than the young men here, and I’m keener to know which of our young men are likely to turn out well. That’s what I look into myself, as far as I can, and I ask the others whom I see the young men wanting to spend time with. And quite a lot of them come to you, 143e and rightly so: you deserve it for your geometry, among other things. So if you’ve come across anyone worth mentioning, I’d be glad to hear about him.

TheodorusWell, Socrates, it’s very much worth my telling and your hearing what a boy I’ve come across among your fellow citizens. If he were good-looking, I’d be very afraid to speak of him, in case anyone thought I was in love with him. As it is—and don’t be offended with me—he’s not good-looking. He looks like you, with his snub nose and his bulging eyes, though he has these features less than you do. 144a So I speak without fear. Believe me, of all the people I’ve ever met—and I’ve spent time with a great many—I’ve never yet come across anyone with such an amazingly good nature.

SocratesThat’s good news. And whose son is he, among our citizens?

TheodorusI’ve heard the name, but I don’t remember it. But 144c actually, he’s the one in the middle of the group coming toward us. Just now he and these friends of his were oiling themselves in the outer running track, and now I think they’ve finished and are coming this way. See if you recognize him.

SocratesI do. He’s the son of Euphronius of Sunium—exactly the sort of man, my friend, you describe his son as being, and well thought of in other ways too. What’s more, he left a very large estate. But I don’t know the boy’s name.note

TheodorusHis name is Theaetetus, Socrates. As for the estate, I think some trustees have squandered it. Still, he’s amazingly generous with money too, Socrates.

SocratesHe sounds a thoroughly noble person. Tell him to come and sit here by me.

TheodorusI will. Theaetetus, come here beside Socrates.

SocratesYes, do, Theaetetus, so that I can take a look at myself too and see what sort of face I have. Theodorus says 144e mine is like yours. But suppose each of us had a lyre and he said they were tuned alike: would we believe him straight away, or would we look into whether he was speaking as a musician?

TheaetetusWe’d look into it.

SocratesAnd if we found he was one, we’d believe him, but if he knew nothing of music, we’d distrust him?

TheaetetusThat’s right.

SocratesAnd now, I think, if we care at all about our faces being 145a alike, we must look into whether he’s speaking as someone skilled in drawing or not.

TheaetetusI think so.

SocratesWell, is Theodorus a painter?

TheaetetusNo, not so far as I know.

SocratesNot a geometer either?

TheaetetusOh, he certainly is, Socrates.

SocratesAnd an astronomer, and skilled in arithmetic and music, and everything that belongs to education?

TheaetetusI think so.

SocratesSo if he says we’re alike in some bodily feature, praising or criticizing us in some way, it isn’t really worth paying attention to him.

TheaetetusPerhaps not.

SocratesBut what if he were praising the soul of one of us for excellence and wisdom? Wouldn’t it be worthwhile for the one who heard it to be eager to look closely at the one praised, and for that one to be eager to show himself?

TheaetetusVery much so, Socrates.

SocratesThen it’s time, my dear Theaetetus, for you to show yourself and for me to look. Believe me, Theodorus has praised a lot of people to me, foreigners and citizens alike, but he’s never yet praised anyone the way he praised you just now.

TheaetetusThat would be nice, Socrates. But make sure he wasn’t 145c joking.

SocratesThat isn’t Theodorus’s way. Now don’t go back on what we’ve agreed on the excuse that he’s joking, or he may be forced to give evidence under oath—and nobody is going to charge him with perjury in any case. Take heart and stand by the agreement.

TheaetetusWell, I must do it, if you think so.

SocratesTell me, then: you’re learning some geometry from Theodorus, I take it?

TheaetetusI am.

SocratesAnd some astronomy and harmony and arithmetic?

TheaetetusI’m certainly trying.

SocratesSo am I, my boy, from him and from anyone else I think knows something about these things. But even so, though I’m reasonably well off in other respects, there’s a little thing I’m puzzled about, which I must look into with you and the others here. So tell me: isn’t learning becoming wiser about what one is learning?

TheaetetusOf course.

SocratesAnd it’s by wisdom, I suppose, that the wise are wise.

TheaetetusYes.

SocratesAnd this doesn’t differ at all from knowledge, does it?

TheaetetusWhat doesn’t?

SocratesWisdom. Or aren’t people wise about just the things they have knowledge of?

TheaetetusOf course.

SocratesSo knowledge and wisdom are the same thing?

TheaetetusYes.

SocratesWell, this is exactly what I’m puzzled about and can’t adequately grasp by myself: what on earth knowledge actually is. 146a So can we say what it is? What do you all say? Which of us will speak first? Whoever gets it wrong, and whoever keeps getting it wrong, will sit down and be “donkey,” as children playing ball say; and whoever comes through without a mistake will be our king and order us to answer whatever he likes. Why so quiet? I hope, Theodorus, my love of argument isn’t making me rude, in my eagerness to get us talking and becoming friendly and sociable with one another?

TheodorusSomething like that would be far from rude, Socrates. But tell one of the boys to answer you. I’m not used to this kind of conversation, and I’m past the age for getting used to it. It would suit them, though, and they’d improve a great deal more; youth really can improve at anything. So, as you began, don’t let Theaetetus go—ask him.

SocratesYou hear what Theodorus says, Theaetetus. I don’t think you’ll want 146c to disobey him, and it isn’t right, in matters like these, for a younger man to disobey the orders of a wise one. So answer well and nobly: what do you think knowledge is?

TheaetetusWell, I must, Socrates, since you both tell me to. In any case, if I make a mistake, you’ll correct me.

SocratesCertainly, if we can.

TheaetetusWell then, I think that the things one might learn from Theodorus are kinds of knowledge—geometry and the subjects you went through just now— 146d and then shoemaking and the crafts of the other craftsmen too: all of these together, and each of them, are nothing other than knowledge.

SocratesHow noble and generous of you, my friend! Asked for one thing, you give many, and a varied assortment instead of something simple.

TheaetetusWhat do you mean by that, Socrates?

SocratesProbably nothing. But I’ll tell you what I think. When you say “shoemaking,” you don’t mean anything other than knowledge of making shoes, do you?

TheaetetusNothing else.

SocratesAnd when you say “carpentry”? Anything other than knowledge of making wooden furniture?

TheaetetusNo, not that either.

SocratesSo in both cases you’re defining what each is knowledge of?

TheaetetusYes.

SocratesBut what you were asked, Theaetetus, wasn’t that—what knowledge is knowledge of, or how many kinds of knowledge there are. We didn’t ask because we wanted to count them, but to know what knowledge itself is. Or am I talking nonsense?

TheaetetusNo, you’re quite right.

SocratesNow consider this too. Suppose someone asked us about something ordinary and everyday—about mud, for example, what it is. If we answered him, “potters’ mud, and oven-makers’ mud, and brickmakers’ mud,” wouldn’t we be ridiculous?

TheaetetusPerhaps.

SocratesFirst, I suppose, for thinking that the questioner understands anything from our answer when we say “mud,” whether we add “the 147b figurine-makers’” or any other craftsmen’s. Or do you think anyone understands the name of something when he doesn’t know what it is?

TheaetetusNot at all.

SocratesThen someone who doesn’t know what knowledge is doesn’t understand “knowledge of shoes” either.

TheaetetusNo.

SocratesSo someone who is ignorant of knowledge doesn’t understand shoemaking, or any other craft.

TheaetetusThat’s so.

SocratesThen it’s a ridiculous answer to someone who asks what knowledge is, to give him the name of some craft. The answer gives “knowledge of 147c something,” and that’s not what was asked.

TheaetetusIt seems so.

SocratesSecond, when it’s possible to give a plain, short answer, it takes an endless roundabout road. In the question about mud, for example, it would be plain and simple to say that mud would be earth mixed with liquid, and to let go of whose mud it is.

TheaetetusPut like that, Socrates, it now seems easy. But you may be asking the sort of thing that occurred to us ourselves the other day while we were 147d talking—me and your namesake here, Socrates.note

SocratesWhat was that, Theaetetus?

TheaetetusTheodorus here was drawing diagrams for us about powers, showing that the powers of three square feet and of five square feet are not commensurable in length with the one-foot line, and taking each one in turn like that up to the power of seventeen square feet; and there, for some reason, he got stuck. So it occurred to us, since the powers seemed to be unlimited in number, to try to collect them into one thing by which we could 147e call all these powers.note

SocratesAnd did you find anything like that?

TheaetetusI think we did. But you look at it too.

SocratesGo on.

TheaetetusWe divided all number into two. The number that can come out as an equal number times an equal number we likened to the square in shape, and called it square and equal-sided.

SocratesWell done.

TheaetetusThe numbers in between, then—which include three and 148a five and every number that can’t come out as an equal times an equal, but comes out either as a larger times a smaller or a smaller times a larger, and is always enclosed by a larger and a smaller side—we likened to the oblong shape, and called oblong number.

SocratesExcellent. But what came next?

TheaetetusAll the lines that form the square of an equal-sided plane number we defined as length; all those that form the square of an oblong number, 148b as powers, since they aren’t commensurable with the others in length, but only in the plane areas they have the power to produce. And there’s another thing of the same kind about solids.

SocratesSuperb, boys! So I don’t think Theodorus will be liable for false testimony.

TheaetetusStill, Socrates, what you’re asking about knowledge, I couldn’t answer the way I did about length and power. And yet that seems to me the sort of thing you’re looking for. So Theodorus turns out to be a liar after all.

SocratesWell now, suppose he had praised you for running and said he’d never come across a young man so good at running, and then you raced and were beaten by the fastest runner in his prime: do you think his praise would be any less true?

TheaetetusNo, I don’t.

SocratesBut do you think finding out what knowledge is, as I was saying just now, is a small thing, and not something for those who are in every way at the top?

TheaetetusGood heavens, I think it’s for those at the very top.

SocratesThen take heart about yourself, and believe that Theodorus 148d is right, and do your utmost, both about other things and about knowledge, to get hold of an account of what it actually is.

TheaetetusIf it’s a matter of effort, Socrates, it’ll come to light.

SocratesCome on, then—you showed the way well just now—try to imitate your answer about the powers: just as you gathered them, many as they were, into one form, so too try to address the many kinds of knowledge with one account.

TheaetetusBut believe me, Socrates, I’ve often tried to look into it, when I heard reports of the questions you were asking. But I can’t convince myself that I have anything adequate to say, or hear anyone else speak about it the way you require; and yet I can’t stop worrying about it either.

TheaetetusI don’t know, Socrates. I’m just telling you what I’ve been going through.

SocratesWell, you absurd boy, haven’t you heard that I’m the son of a very fine and formidable midwife, Phaenarete?note

TheaetetusYes, I have heard that.

SocratesAnd have you also heard that I practice the same art?

TheaetetusNever.

SocratesWell, believe me, I do. But don’t give me away to the others. It’s escaped their notice, my friend, that I have this art. They don’t know it, so they don’t say that about me; they say I’m utterly strange and that I reduce people to perplexity. Have you heard that too?

TheaetetusI have.

SocratesShall I tell you the reason for it?

TheaetetusYes, please.

SocratesThen think about the whole business of midwives, how it is with them, and you’ll more easily understand what I mean. You know, I suppose, that none of them attends other women in childbirth while she herself is still conceiving and giving birth; only those who are no longer able to give birth do.

TheaetetusCertainly.

SocratesThey say the cause of this is Artemis, because, though childless, she has been allotted childbirth as her province. She didn’t give midwifery to barren women, 149c because human nature is too weak to master a craft in matters it has no experience of; but she assigned it to those who are past bearing children because of their age, honoring their likeness to herself.note

TheaetetusThat’s likely.

SocratesAnd isn’t this likely too, even necessary: that midwives know better than anyone else whether women are pregnant or not?

TheaetetusCertainly.

SocratesWhat’s more, by giving drugs and 149d singing incantations, midwives can bring on the pains of labor and make them milder if they want to; they bring women who are having a difficult labor to give birth, and, if it seems best to miscarry while the fetus is young, they bring on a miscarriage.

TheaetetusThat’s so.

SocratesAnd have you noticed this about them too, that they are also the cleverest matchmakers, being thoroughly wise about recognizing what sort of woman should be with what sort of man in order to bear the best children?

TheaetetusI didn’t know that at all.

SocratesWell, believe me, they’re prouder of this than of 149e cutting umbilical cords. Think about it: do you think it belongs to the same craft or a different one to tend and harvest the fruits of the earth and also to know what kind of plant or seed should be sown in what kind of soil?

TheaetetusNo, the same one.

SocratesAnd in the case of a woman, my friend, do you think there’s one craft for this sort of thing and another for the harvest?

TheaetetusIt doesn’t seem likely.

SocratesNo. But because of the unjust and unskilled bringing together of man and woman, which is called procuring, midwives, being respectable women, avoid matchmaking too, for fear that through it they may fall under that charge. Yet it’s surely only genuine midwives who can properly make matches.

TheaetetusIt seems so.

SocratesSo much, then, for the midwives’ role. But it is less than my performance. For women don’t sometimes 150b give birth to phantoms and sometimes to real children, with the difference hard to tell. If they did, the greatest and finest task of midwives would be to judge what is real and what isn’t. Don’t you think so?

TheaetetusI do.

SocratesMy art of midwifery has everything theirs has, but it differs in that I deliver men, not women, and in that I oversee their souls in labor, not their bodies. And the greatest thing in 150c our art is being able to test, in every way, whether the young man’s thinking is giving birth to a phantom and a falsehood, or to something fertile and true. Because I have this in common with midwives: I’m barren of wisdom. Many people have reproached me before now for questioning others while making no pronouncement about anything myself, because I have no wisdom in me—and the reproach is true. The reason is this: the god compels me to act as midwife but has prevented me from giving birth.

TheaetetusWell, Socrates, with you urging me on like that, it would be shameful not to do my utmost to say what 151e I can. It seems to me, then, that someone who knows something perceives what he knows, and, as it appears now at least, knowledge is nothing other than perception.

SocratesWell done, my boy, that’s a noble answer: that’s how you should speak when you declare yourself. But come, let’s examine it together, to see whether it turns out to be fertile or a wind-egg. Knowledge, you say, is perception?note

TheaetetusYes.

TheaetetusI’ve read it, many times.

SocratesDoesn’t he mean something like this: that as each thing appears to me, so it is for me, and as it appears to you, so in turn it is for you—and you and I are each a human being?

TheaetetusYes, that’s what he says.

SocratesWell, it’s likely that a wise man isn’t talking nonsense. So let’s follow him. Isn’t it the case that sometimes, when the same wind is blowing, one of us feels cold and the other doesn’t? Or one feels slightly cold and the other very cold?

TheaetetusCertainly.

SocratesThen shall we say that at that moment the wind itself, by itself, is cold or not cold? Or shall we be persuaded by Protagoras that it is cold for the one who feels cold, and not for the one who doesn’t?

TheaetetusIt seems we should.

SocratesAnd it appears that way to each of them?

TheaetetusYes.

SocratesAnd “appears” is the same as “is perceived”?

TheaetetusIt is.

SocratesThen appearing and perception are the same, in the case of hot things and everything of that kind. For as each person perceives things, so they are likely to be for each person.

TheaetetusIt seems so.

SocratesThen perception is always of what is, and it is free from falsehood, since it is knowledge.

TheaetetusApparently.

SocratesThen, by the Graces, was Protagoras some kind of all-wise man, who spoke this to the rest of us, the great rabble, in riddles, while telling the truth to his students in secret?

TheaetetusWhat do you mean by that, Socrates?

SocratesI’ll tell you, and it’s no ordinary account: that nothing is one thing, itself by itself, and you can’t correctly call it anything or any sort of thing. If you call it large, it will also appear small, and if heavy, light, and so on with everything, since nothing is one thing or something or any sort of thing. It’s from movement and motion and mixture with one another that all the things we say “are” come to be—though we’re wrong to speak of them that way, 152e since nothing ever is; things are always coming to be.

TheaetetusI do.

SocratesThen who could still dispute with such an army, and with Homer as its general, without making himself ridiculous?

TheaetetusIt wouldn’t be easy, Socrates.

SocratesNo, Theaetetus, it wouldn’t. Here, in fact, are signs enough in support of the account: motion supplies what seems to be, and coming to be, while rest supplies not being and perishing. Heat and fire, which generate and govern everything else, are themselves generated from movement and friction, and these two are motions. Or aren’t these the origins of fire?

TheaetetusThey certainly are.

SocratesAnd the race of living creatures grows from these same things.

TheaetetusOf course.

SocratesWell then, isn’t the condition of bodies destroyed by rest and idleness, and preserved, for the most part, by exercise and motion?

TheaetetusYes.

SocratesAnd isn’t it by learning and practice, which are motions, that the condition of the soul acquires things learned and is preserved and gets better; while through rest, which is lack of practice and 153c lack of learning, it learns nothing and forgets whatever it has learned?

TheaetetusVery much so.

SocratesSo one thing, motion, is good for both soul and body, and the other the opposite?

TheaetetusIt seems so.

SocratesDo I need to go on and tell you about still air and calm seas and the like—that the stillness rots and destroys, while the other preserves? And to cap it all, must I compel you to agree that by the golden cord Homer means nothing other than the sun, 153d and is showing that as long as the heavens and the sun go round in their motion, everything among gods and humans exists and is preserved, but if this were to stop as if tied fast, all things would be destroyed and, as the saying goes, everything would be turned upside down?note

TheaetetusI think, Socrates, it shows just what you say.

SocratesThen take it this way, my excellent friend. Start with the eyes: what you call white color isn’t itself some separate thing outside your eyes, or in your eyes either. Don’t 153e assign it any place, because then it would of course be somewhere in position, staying put, and it wouldn’t come to be in the process of becoming.

TheaetetusThen how?

SocratesLet’s follow the account we gave just now and posit that nothing is one thing, itself by itself. In that way black and white and any other color will turn out to have come to be from the eyes meeting the appropriate movement, and what we say each color 154a is will be neither what meets nor what is met, but something in between, which has come to be private to each. Or would you insist that each color appears to a dog, or any other animal, just as it appears to you?

TheaetetusGood heavens, no, I wouldn’t.

SocratesWell, does anything appear the same to another human being as it does to you? Are you firmly convinced of that? Or much rather that it doesn’t appear the same even to you yourself, because you are never in the same condition as yourself?

TheaetetusI think that rather than the other.

SocratesNow if what we measure ourselves against or touch were large or white or hot, it would never have become different by encountering something else, provided it didn’t change in itself. And again, if what does the measuring or touching were any of these things, it wouldn’t have become different when something else came up to it or was affected in some way, if it were not itself affected. As things are, my friend, we find ourselves rather casually forced to say amazing and ridiculous things, as Protagoras would say, and everyone who undertakes to say what he does.

TheaetetusHow do you mean? What sort of things?

SocratesTake a small example and you’ll know everything I mean. Take six dice: if you put four beside them, we say they are more than the four, half as many again; but if you put twelve, we say they are fewer—half as many. And it isn’t tolerable to say anything else. Or will you tolerate it?

TheaetetusNo, I won’t.

SocratesWell then, suppose Protagoras or someone else asks you, “Theaetetus, is it possible for anything to become larger or more in any way other than by being increased?” What will you answer?

TheaetetusIf I answer what I think in response to this 154d question, Socrates, I’ll say it isn’t possible. But if I answer with an eye to the earlier one, taking care not to contradict myself, I’ll say it is.

SocratesBy Hera, my friend, that’s a fine answer, and inspired. But it seems that if you answer that it is possible, we’ll get something out of Euripides: our tongue won’t be refuted, but our mind will.note

TheaetetusThat’s true.

SocratesNow if you and I were clever and wise and had examined everything in our minds, we would by now be spending the rest of our time 154e testing each other out of sheer abundance, coming together like sophists for this sort of battle and knocking each other’s arguments down with arguments. As it is, being ordinary people, we’ll want first to look at our thoughts themselves in relation to themselves and see what they really are, and whether they agree with one another or not in any way at all.

TheaetetusThat’s certainly what I would want.

SocratesAnd so do I. Since that’s how things stand, won’t we look at it again quietly, as people with plenty of time on their hands, 155a not getting irritated but really examining ourselves, to see what on earth these apparitions in us are? Examining the first of them, we’ll say, I think, that nothing could ever become larger or smaller, either in bulk or in number, as long as it was equal to itself. Isn’t that so?

TheaetetusYes.

SocratesAnd second, that a thing to which nothing was added and from which nothing was taken away would never either increase or diminish, but would always be equal.

TheaetetusAbsolutely.

SocratesAnd third, isn’t it impossible for something to be later what it wasn’t before, without having become it and coming to be?

TheaetetusIt does seem so.

SocratesNow these three agreements, I think, are fighting among themselves in our soul when we speak about the dice, or when we say that I, at my age, neither having grown nor having undergone the opposite, am within a year larger than you, who are young, and later smaller—not because anything has been 155c taken away from my bulk, but because you have grown. For then I am later what I was not before, without having become it. For without coming to be it is impossible to have become, and without losing any of my bulk I could never have become smaller. And there are thousands upon thousands of other cases like this, if we are going to accept these. You follow me, I take it, Theaetetus. You certainly seem to me to be no stranger to this sort of thing.

TheaetetusYes, by the gods, Socrates, and I’m extraordinarily amazed at what on earth these things are; sometimes when I really look at them I get quite dizzy.

TheaetetusNot yet, I think.

SocratesThen will you be grateful to me if I help you search out the truth hidden in the thinking of a famous man—or rather, famous men— 155e and get it out of them?

TheaetetusHow could I not be? Very grateful indeed.

SocratesThen look around and make sure none of the uninitiated are listening. These are the people who think that nothing exists except what they can grip tightly with both hands, and who don’t accept actions and processes of becoming and everything invisible as part of being.

TheaetetusWell, Socrates, they are hard and 156a stubborn people you’re talking about.

SocratesYes, my boy, they’re very crude indeed. But there are others, much more refined, whose mysteries I am going to tell you. Their first principle, on which everything we were saying just now also depends, is this: that the universe was motion and nothing besides, and that there are two kinds of motion, each unlimited in number, one having the power to act, the other to be acted upon. From the intercourse and friction of these with each other come offspring, unlimited in number, 156b but twins: on the one hand what is perceived, on the other a perception, which always emerges and is born together with what is perceived.

TheaetetusNot really, Socrates.

SocratesWell, watch and see whether it can be finished off somehow. What it means to say is that all these things are in motion, as we say, but that there is speed and slowness in their motion. What is slow has its motion in the same place and in relation to what comes near it, 156d and in that way it generates; but the offspring generated in this way are faster. For they travel, and their motion naturally consists in travel.

TheaetetusI don’t know, Socrates. I can’t even make out, where you’re concerned, whether you’re saying these things because you believe them or you’re testing me.

SocratesYou don’t remember, my friend, that I don’t know anything of this sort and don’t claim any of it as my own—I am barren of it. I’m acting as your midwife, and that’s why I’m singing incantations and serving up 157d tastes of each of the wise, until I can help bring your belief out into the light. Once it has been brought out, I’ll examine whether it turns out to be a wind-egg or fertile. So take heart and be steadfast, and answer well and bravely whatever appears to you about what I ask.

TheaetetusGo ahead and ask.

SocratesThen tell me again whether you like the view that nothing is, but that good and beautiful and all the things we went through just now are always coming to be.

TheaetetusWell, since I’ve heard you go through it like this, it seems to me amazingly reasonable, and I think it should be accepted as you’ve set it out.

SocratesThen let’s not leave out what remains of it. What remains is dreams and illnesses, madness in particular, and all the cases of what is called mishearing or misseeing or misperceiving in some other way. You know, I suppose, that in all of these the account we went through just now is by general agreement thought to be refuted, 158a on the grounds that in them we certainly have false perceptions, and that it’s far from true that what appears to each person also is; on the contrary, none of what appears is.

TheaetetusWhat you say is very true, Socrates.

SocratesThen what account is left, my boy, for someone who holds that perception is knowledge and that what appears to each person also is, for the person to whom it appears?

TheaetetusI hesitate to say I don’t know what to say, Socrates, because you scolded me just now for saying so. But I really 158b couldn’t dispute that people who are deranged or dreaming judge falsely, when some of them think they are gods and others imagine in their sleep that they have wings and are flying.note

SocratesThen don’t you have in mind this other dispute about them either, especially about dreaming and being awake?

TheaetetusWhat dispute?

SocratesThe one I think you’ve often heard people raise when they ask what proof one could give if someone asked, right now, at the present moment, whether we are asleep and dreaming all our thoughts, 158c or awake and talking to each other in waking life.

TheaetetusWell, Socrates, it’s hard to see what proof one should use to show it. Everything corresponds exactly, as if in counterpart. Nothing prevents us from seeming to talk to each other in our sleep too about what we’ve just been discussing; and when in a dream we seem to be telling dreams, the likeness of the one to the other is uncanny.

SocratesSo you see that it isn’t hard to raise a dispute, when 158d people even dispute whether it’s waking or dreaming. And since the time we spend asleep is equal to the time we spend awake, in each our soul fights hard for whatever beliefs are present at the time as being true above all, so that for an equal time we say these things are real and for an equal time those, and we insist on each with equal conviction.

TheaetetusAbsolutely.

SocratesAnd doesn’t the same account hold for illnesses and madness, except that the time isn’t equal?

TheaetetusThat’s right.

SocratesWell then, will the truth be determined by length or shortness of time?

TheaetetusThat would be ridiculous in many ways.

SocratesBut do you have anything else clear to point to, to show which of these judgments are true?

TheaetetusI don’t think so.

SocratesThen listen to me tell you what those who define whatever seems at any time as true for whoever it seems to would say about them. They speak, I think, by asking like this: “Theaetetus, can something that is completely different have the same power in any way as the other thing? And let’s not take what we’re asking about to be in one way the same and in another way different, but wholly different.”

TheaetetusThen it’s impossible for it to have anything the same, either in power or in anything else, when it’s entirely different.

SocratesThen mustn’t we also agree that such a thing is unlike?

TheaetetusI think so.

SocratesSo if anything happens to become like or unlike something, either itself or something else, shall we say that in becoming like it becomes the same, and in becoming unlike, different?

TheaetetusWe must.

SocratesNow we were saying earlier that the things that act are many, indeed unlimited, and so are the things that are acted upon?

TheaetetusYes.

SocratesAnd also that a thing mixed with one thing and then with another will produce, not the same things, but different ones?

TheaetetusCertainly.

SocratesThen let’s now speak of me and you and other things according to the same account: Socrates healthy, and again Socrates sick. Shall we say that the latter is like or unlike the former?

TheaetetusYou mean Socrates sick, this as a whole, compared with that as a whole, Socrates healthy?

SocratesYou’ve taken my point perfectly: that’s exactly what I mean.

TheaetetusUnlike, surely.

SocratesAnd so different, just as it is unlike?

TheaetetusNecessarily.

SocratesAnd you’ll say the same about Socrates asleep, and in all the states we went through just now?

TheaetetusI will.

SocratesNow take each of the things whose nature it is to act on something. When it gets hold of Socrates healthy, won’t it treat me as one person, and when it gets hold of Socrates sick, as a different one?

TheaetetusWhy wouldn’t it?

SocratesAnd in each case the two of us, I who am acted on and that thing which acts, will generate different things?

TheaetetusOf course.

SocratesNow when I drink wine while I’m healthy, it appears pleasant and sweet to me?

TheaetetusYes.

SocratesYes, because on what we agreed earlier, the thing that 159d acts and the thing acted on have generated sweetness and a perception, both moving at once. The perception, being on the side of what is acted on, has made the tongue perceiving; the sweetness, on the side of the wine and moving about it, has made the wine both be and appear sweet to the healthy tongue.

TheaetetusYes, that’s certainly how we agreed on the earlier points.

SocratesBut when it gets hold of me sick, isn’t it the case, first of all, that in truth it hasn’t got hold of the same man? It has come upon someone unlike.

TheaetetusYes.

SocratesThen this sort of Socrates and the drinking of the wine have generated different things again: around the tongue, a perception of bitterness; around the wine, a bitterness coming into being and moving. And they’ve made the wine not bitterness but bitter, and me not perception but perceiving?

TheaetetusExactly.

SocratesSo I will never become like this in perceiving anything else; a different object means a different perception, and it makes the perceiver of a different kind 160a and a different person. Nor will the thing that acts on me ever, by meeting someone else and generating the same thing, become like this itself; by generating something else from someone else, it will become of a different kind.

TheaetetusThat’s so.

SocratesNor again will I become like this for myself, or it become like that for itself.

TheaetetusNo, they won’t.

SocratesBut when I become perceiving, I must become perceiving of something; to become perceiving, yet perceiving nothing, is 160b impossible. And the thing, in turn, must become so for someone, when it becomes sweet or bitter or anything of that sort; to become sweet, yet sweet to no one, is impossible.

TheaetetusAbsolutely.

SocratesWhat’s left, I think, is that we are, if we are, or become, if we become, for each other, since necessity binds our being together, but binds it to nothing else, and not to ourselves either. So what’s left is that we’re bound to each other. Hence if anyone speaks of something as being, he must say it is for someone, or of something, or in relation to something; and the same if he speaks of it as becoming. But that anything is or becomes in and of itself he must neither 160c say himself nor accept when someone else says it, as the account we’ve gone through indicates.

TheaetetusAbsolutely, Socrates.

SocratesThen since what acts on me is for me and not for anyone else, am I not also the one who perceives it, and no one else?

TheaetetusOf course.

SocratesSo my perception is true for me, since it always belongs to my being; and I am the judge, as Protagoras says, of the things that are, for me, that they are, and of the things that are not, that they are not.

TheaetetusIt seems so.

SocratesThen if I’m free of falsehood and don’t stumble in my thinking about what is or what becomes, how could I fail to have knowledge of the things I perceive?

TheaetetusThere’s no way you could.

SocratesSo it was a splendid thing you said, that knowledge is nothing other than perception. And it has all come to the same thing: according to Homer and Heraclitus and that whole tribe, everything is in motion like flowing streams; according to Protagoras, wisest of men, a human being is the measure of all things; and according to 160e Theaetetus, given that this is how things are, perception turns out to be knowledge. Isn’t that right, Theaetetus? Shall we say this is your newborn child, as it were, and my delivery? Or how would you put it?

TheaetetusIt has to be so, Socrates.

SocratesWell then, it seems we’ve managed at last, with difficulty, to give birth to this, whatever it turns out to be. But after the birth we must hold its naming rite and really run around it in a circle, in argument, making sure we don’t overlook that what’s been born isn’t worth rearing, 161a but an empty wind-egg, a falsehood. Or do you think your child must be reared no matter what, and not exposed? Or will you bear to see it put to the test, and not get terribly angry if someone takes it from you, though it’s your first?note

TheodorusTheaetetus will bear it, Socrates; he’s not bad-tempered at all. But for heaven’s sake, tell me: in what way is it not so after all?

SocratesYou’re a real lover of arguments, Theodorus, and a good fellow, to think I’m some sort of sack of arguments and can easily pull one out 161b and say that this isn’t so after all. You don’t notice what’s happening: none of the arguments comes from me; they always come from the person I’m talking with. I know nothing more than a little: just enough to take an argument from someone else who is wise and receive it fairly. So now too I’ll try to do that with this boy, not to say anything myself.

TheodorusThat’s better put, Socrates. Do it that way.

SocratesDo you know, then, Theodorus, what surprises me about your friend Protagoras?

TheodorusWhat’s that?

SocratesMost of what he said I like very much, that what seems to each person also is so. But I was surprised by the beginning of his account: that at the opening of his Truth he didn’t say “a pig is the measure of all things,” or “a baboon,” or some even stranger creature that has perception. Then he would have begun addressing us in a grand and quite contemptuous style, showing that while we were admiring him like a god for his wisdom, he 161d was actually no better in understanding than a tadpole, let alone any other human being. Or what should we say, Theodorus?

TheodorusSocrates, the man was my friend, as you said just now. So I wouldn’t want Protagoras refuted through my agreeing, nor again to resist you against what I think. So take Theaetetus again. In any case he seemed just now to be following you very nicely.

SocratesTheodorus, if you went to Sparta and visited the wrestling grounds, would you think it right to watch others naked, some of them in poor shape, and not strip off beside them and show your own figure in turn?

TheodorusWhy not, if they’d leave it to me and listen to me? Just as now I think I’ll persuade you all to let me watch, and not drag me to the gymnasium, stiff as I already am, but to wrestle with the one who’s younger and more supple.

SocratesWell, Theodorus, if that’s dear to you, it’s no enemy 162c to me, as the proverb-makers say. So back we must go to wise Theaetetus. Tell me first, Theaetetus, about what we went through just now: aren’t you surprised if you’re suddenly going to turn out no worse in wisdom than any human being, or even any god? Or do you think the Protagorean measure applies any less to gods than to human beings?

TheaetetusBy Zeus, I don’t. And as for what you’re asking, I’m very surprised. When we were going through the way they say that what seems 162d to each person also is, for the one it seems to, it seemed to me very well said. But now, all of a sudden, it has flipped over to the opposite.

SocratesThat’s because you’re young, my dear boy, and so you’re quick to listen to crowd-pleasing speeches and be persuaded. To this Protagoras, or someone else on his behalf, will say: “My fine boys and old men, you sit together making speeches to the crowd, and you drag in the gods, 162e whom I leave out of my speaking and writing, whether they exist or do not. And you say what the many would be glad to hear: how terrible it would be if each human being were no different in wisdom from any grazing beast. But you state no demonstration or proof whatever; you rely on likelihood. If Theodorus or any other geometer were willing to do geometry relying on that, he wouldn’t be worth a thing. So consider, you and Theodorus, whether you’ll accept arguments stated with plausible talk and likelihoods 163a about matters this important.”note

TheaetetusBut it wouldn’t be just, Socrates; neither you nor we would say so.

SocratesThen we must look at it another way, it seems, as your account and Theodorus’s say.

TheaetetusYes, another way, by all means.

SocratesLet’s look at it like this, then: whether knowledge and perception are the same or different. That’s what our whole argument has been aiming at, I suppose, and it was for its sake that we stirred up all these many strange things. Isn’t it?

TheaetetusAbsolutely.

SocratesWell then, shall we agree that whatever we perceive by seeing or hearing, all of it, we also know at the same time? For example, before we’ve learned the language of foreigners, shall we say we don’t hear them when they speak, or that we both hear and know what they’re saying? And again, when we don’t know our letters and look at them, shall we insist that we don’t see them, or that we know them, if we see them?

TheaetetusJust that much of them, Socrates, that we see and hear, we’ll say we know. In the one case we see and know the shape and the color; in the other we hear and at the same time know the 163c high and low pitch. But what the schoolteachers and interpreters teach about them we neither perceive by seeing or hearing, nor know.

SocratesExcellent, Theaetetus. It’s not worth my disputing that with you, so that you can grow. But look, here’s another thing coming at us, and consider how we’ll fend it off.

TheaetetusWhat’s that?

SocratesThis sort of thing. Suppose someone asked: “If a person has once come to know something, and still has the memory of it and keeps it, is it possible that at the moment he remembers it he doesn’t know the very thing he remembers?” I’m being long-winded, it seems, when all I want to ask is whether someone who has learned something and remembers it doesn’t know it.

TheaetetusHow could that be, Socrates? What you’re describing would be a monstrosity.

SocratesAm I talking nonsense, then? But consider. Don’t you say that seeing is perceiving, and sight is perception?

TheaetetusI do.

SocratesThen someone who has seen something has come to know what he saw, according to what we said just now?

TheaetetusYes.

SocratesWell? You do say there’s such a thing as memory?

TheaetetusYes.

SocratesMemory of nothing, or of something?

TheaetetusOf something, surely.

SocratesOf things one has learned and perceived, things of that sort?

TheaetetusOf course.

SocratesAnd what someone has seen, he sometimes remembers, I suppose?

TheaetetusHe does.

SocratesEven with his eyes shut? Or does he forget it when he does that?

TheaetetusBut that would be a terrible thing to say, Socrates.

SocratesYet we have to say it, if we’re going to save the earlier account. If not, it’s done for.

TheaetetusI suspect so too, by Zeus, but I don’t quite grasp it. Tell me how.

SocratesLike this. The one who sees has come to know what he sees, we say; for sight and perception and knowledge have been agreed to be the same.

TheaetetusCertainly.

SocratesBut the one who has seen and come to know what he saw, if he shuts his eyes, remembers it but doesn’t see it. Right?

TheaetetusYes.

SocratesBut “doesn’t see” is “doesn’t know,” if “sees” is “knows.”

TheaetetusTrue.

SocratesSo the result is that someone who has come to know something doesn’t know it though he still remembers it, since he doesn’t see it. And that’s what we said would be a monstrosity, if it happened.

TheaetetusWhat you say is perfectly true.

SocratesSo something impossible evidently follows if one says that knowledge and perception are the same.

TheaetetusIt seems so.

SocratesThen we must say that each is different.

TheaetetusIt looks that way.

SocratesThen what could knowledge be? We have to start again from the beginning, it seems. And yet, Theaetetus, what are we about to do?

TheaetetusAbout what?

SocratesWe seem to me to be like a cock of poor breeding: we’ve jumped away from the argument and started crowing before we’ve won.

TheaetetusHow so?

SocratesWe seem to have been content, like professional debaters, to reach agreement on the basis of agreements about words, and to have got the better of the argument by some such means. And though we say we’re not contestants but philosophers, 164d we don’t notice we’re doing the same things as those clever fellows.

TheaetetusI still don’t understand what you mean.

SocratesWell, I’ll try to make clear what I have in mind about them. We asked whether someone who has learned something and remembers it doesn’t know it; and having shown that someone who saw and then shut his eyes remembers but doesn’t see, we showed that he doesn’t know and at the same time remembers, and that this was impossible. And so the Protagorean tale perished, and yours along with it, the one about knowledge and perception being the same.

TheaetetusApparently.

SocratesNot so, I think, my friend, if the father of the other tale were alive; he’d have done a lot to defend it. As it is, it’s an orphan, and we’re dragging it through the mud. Not even the guardians Protagoras left behind are willing to help it, and Theodorus here is one of them. Well then, we’ll risk helping it ourselves, for justice’s sake.

TheodorusIt isn’t I, Socrates, but rather Callias 165a son of Hipponicus who is guardian of his affairs. As for me, somehow I turned rather quickly from bare argument to geometry. But we’ll be grateful to you if you help it.note

SocratesWell said, Theodorus. Then look at my help, at any rate. For someone who didn’t pay attention to the words, the way we’re mostly used to affirming and denying things, might agree to things more terrible than these just now. Shall I tell you how, or Theaetetus?

TheodorusTell us both; but let the younger one answer. 165b If he trips, he’ll disgrace himself less.

SocratesThen I’ll put the most terrible question. It’s something like this, I think: “Can the same person, knowing something, not know what he knows?”

TheodorusWhat shall we answer, then, Theaetetus?

TheaetetusThat it’s impossible, I think.

SocratesNot if you hold that seeing is knowing. For what will you do with an inescapable question, trapped in a well, as the saying goes, when some unflappable man covers with his hand 165c one of your eyes and asks whether you see his cloak with the covered one?

TheaetetusI’ll say not with this one, I suppose, but with the other.

SocratesThen you see and don’t see the same thing at the same time?

TheaetetusIn a way, yes.

Socrates“That’s not what I’m setting you,” he’ll say, “and I didn’t ask about the how. I asked whether what you know you also don’t know. As it is, you’re plainly seeing what you don’t see. And you happen to have agreed that seeing is knowing, and not seeing not knowing. So work out from this what follows for you.”

TheaetetusWell, I work out that it’s the opposite of what I proposed.

SocratesAnd perhaps, my wonderful friend, you’d have suffered more of this sort if someone had gone on to ask you whether it’s possible to know sharply and dimly, and to know from close up but not from afar, and to know the same thing intensely and faintly, and countless other things. A light-armed mercenary in arguments would lie in ambush and ask them, once you’d laid it down that knowledge and perception are the same. He’d attack hearing and smelling and other perceptions like these, and keep refuting you, 165e pressing on and not letting go, until you, lost in wonder at his much-prayed-for wisdom, got your feet tangled up by him; and then, once he’d subdued and tied you up, he’d release you for whatever ransom you and he agreed on. So what argument, you might ask, will Protagoras put forward in support of his own? Shall we try to state it?

TheaetetusCertainly.

SocratesWell, he’ll say all the things we’re saying in his defense, 166a and he’ll come to close quarters, I think, full of contempt for us, and say: This fine Socrates here, when a little boy was asked whether the same person can remember something and at the same time not know it, and got scared, and in his fright said no because he couldn’t see ahead, made me a laughingstock in his arguments. But the truth, Socrates, you lazybones, is this. When you examine any of my views by questioning, if the person questioned gives the answers I would give and is tripped up, then I 166b am refuted; but if he gives different ones, it’s the one questioned himself. For instance, do you think anyone will concede to you that a person’s memory of what he experienced, when he’s no longer experiencing it, is the same sort of experience as he had when he was experiencing it? Far from it.

TheodorusYou’re joking, Socrates. You’ve come to the man’s aid with real youthful vigor.

SocratesKind of you, my friend. Now tell me: did you notice just now how Protagoras was speaking and reproaching us because, 168d carrying on our arguments with a child, we used the boy’s fear to fight against his views? And how he called it a piece of frivolity, and, making much of his measure of all things, urged us to be serious about his account?

TheodorusOf course I noticed, Socrates.

SocratesWell then? Do you tell me to obey him?

TheodorusVery much so.

SocratesYou see, then, that everyone here except you is a child. So if we’re going to obey the man, you and I must question and 168e answer each other and be serious about his account, so that he can’t at least charge us with examining his account while playing around with youngsters.

TheodorusWhat? Wouldn’t Theaetetus follow an argument under investigation better than lots of men with long beards?

SocratesBut not better than you, Theodorus. So don’t think that I must, in every possible way, 169a defend your dead friend, and you in no way at all. Come on, my good man, follow along a little, just until we find out whether you have to be the measure where diagrams are concerned, or whether everyone is as competent in their own eyes as you are in astronomy and the other subjects in which you’re reputed to excel.

TheodorusIt isn’t easy, Socrates, to sit beside you and not give an account. I was talking nonsense just now when I said you’d let me keep my clothes on, and wouldn’t compel me the way the Spartans do. You seem to me, rather, to be going the way of Sciron. 169b The Spartans tell you to leave or strip, but you seem to me to be playing more the part of Antaeus: you don’t let anyone who comes near go until you’ve stripped him and forced him to wrestle in arguments.note

SocratesYou’ve pictured my sickness very well, Theodorus. But I’m tougher than they were. Countless Heracleses and Theseuses, mighty at argument, have met me and given me a thorough beating, but I don’t hold back any the more; 169c so terrible a passion for exercise in these things has got into me. So don’t you begrudge me a bout either, and benefit yourself and me at the same time.

TheodorusI won’t argue any more. Lead on wherever you like. Whatever fate you spin for me in these matters, I must endure being refuted. But I won’t be able to put myself at your disposal beyond what you propose.

SocratesThat far is enough. And watch out especially for this: that we don’t slip into some childish kind of argument without noticing, 169d and someone reproach us for it again.

TheodorusWell, I’ll try, as far as I can.

SocratesThen let’s first get hold again of the same point as before, and see whether we were right or wrong to be dissatisfied when we criticized the account for making each person self-sufficient in understanding, and Protagoras conceded to us that some people are superior when it comes to the better and the worse, and that these are in fact the wise. Weren’t we?

TheodorusYes.

SocratesNow if he himself were here agreeing to it, and it weren’t we 169e who conceded it in helping him, there’d be no need to take it up again and confirm it. But as it is, someone might well rule that we have no authority to agree on his behalf. So it’s better to come to a clearer agreement on this very point; it makes no small difference whether it’s so or otherwise.

TheodorusThat’s true.

SocratesThen let’s get the agreement not through others but from his own statement, 170a as briefly as possible.

TheodorusHow?

SocratesLike this. He says, doesn’t he, that what seems to each person also is, for the one it seems to?

TheodorusYes, he does.

SocratesWell then, Protagoras, we too are stating the judgments of a human being, or rather of all human beings, when we say that there is no one who doesn’t consider himself wiser than others in some things, and others wiser than himself in other things. In the greatest dangers, at any rate, when they’re in trouble on campaign, or in sickness, or in a storm at sea, people treat those in charge in each case like gods, expecting them to be their saviors, 170b though they’re superior in nothing else but knowing. And all of human life, I suppose, is full of people looking for teachers and rulers for themselves, for other living things, and for their work, and of people who think themselves competent to teach and competent to rule. In all these cases, what else shall we say but that human beings themselves consider that wisdom and ignorance exist among them?

TheodorusNothing else.

SocratesAnd they consider wisdom to be true thinking, and ignorance false judgment?

TheodorusOf course.

SocratesThen what are we to make of the account, Protagoras? Shall we say that human beings always judge truly, or sometimes truly and sometimes falsely? Either way, it turns out that they don’t always judge truly, but both truly and falsely. Consider, Theodorus: would any of Protagoras’s followers, or you yourself, be willing to fight it out that no one thinks anyone else is ignorant and judges falsely?

TheodorusNo, Socrates, that’s beyond belief.

SocratesAnd yet that’s the necessity the account comes to, the one that says a human being is the measure of all things.

TheodorusHow so?

SocratesWhen you’ve decided something in your own mind and declare to me your judgment about it, let that be true for you, according to his account. But are the rest of us not allowed to act as judges of your decision? Or do we always decide that you judge truly? Or do countless people, every time, fight you with contrary judgments, holding that your decisions and beliefs are false?

TheodorusBy Zeus, Socrates, “countless thousands” indeed, as Homer says, and they give me all the trouble that people can.note

SocratesWell then? Do you want us to say that you then judge truly for yourself, but falsely for the countless others?

TheodorusIt seems it has to be so, on the account at any rate.

SocratesAnd what about Protagoras himself? Isn’t it necessary that, if neither he himself believed that a human being is the measure, nor did the many, as indeed they don’t, then this truth 171a he wrote is true for no one? And if he believed it, but the majority don’t share his belief, you know that, to begin with, it is not more than it is, by as much as those it doesn’t seem so to outnumber those it does.

TheodorusNecessarily, if it’s going to be and not be according to each judgment.

SocratesNext, it has this most exquisite feature. He, for his part, concedes about his own belief that the belief of those who judge the contrary, by which they consider him mistaken, is true, I suppose, since he agrees that everyone judges things that are.

TheodorusCertainly.

SocratesThen he’d be conceding that his own belief is false, if he agrees that the belief of those who think he’s mistaken is true?

TheodorusNecessarily.

SocratesBut the others don’t concede that they themselves are mistaken?

TheodorusNo, they don’t.

SocratesAnd he, in turn, agrees that this judgment of theirs is true too, from what he has written.

TheodorusApparently.

SocratesSo it will be disputed by everyone, starting from Protagoras; or rather, he’ll agree to it: when he concedes that the person saying the opposite judges truly, 171c then Protagoras himself will concede that neither a dog nor any chance human being is the measure of even one thing he hasn’t learned. Isn’t that so?

TheodorusIt is.

SocratesThen since it’s disputed by everyone, Protagoras’s Truth would be true for no one, neither for anyone else nor for him himself.

TheodorusWe’re running my friend down too hard, Socrates.

SocratesYet it isn’t clear, my friend, that we aren’t also running past what is right. Of course it’s likely that he, being older, is wiser 171d than we are. And if he were to pop his head up out of the ground right here, as far as the neck, he’d very likely convict me many times over of talking nonsense, and you of agreeing, and then sink down again and be off at a run. But we, I think, have to make do with ourselves as we are, and always say what seems so to us. And so now too, shall we say that anyone at all would agree at least to this: that one person is wiser than another, and also more ignorant?

TheodorusIt seems so to me, at any rate.

SocratesAnd that the account would stand firmest in the way 171e we sketched in helping Protagoras: that most things are, for each person, the way they seem, hot, dry, sweet, everything of that type. But if he’ll grant anywhere that one person is superior to another, he’d be willing to say it’s about what is healthy and diseased: that not every woman and child, or animal either, is capable of healing itself by knowing what’s healthy for it; here, rather, one person is superior to another, if anywhere?

TheodorusThat seems right to me.

SocratesAnd in political matters too, fine and shameful, just and unjust, pious and not, whatever each city thinks and lays down as lawful for itself also is so in truth for each; and in these matters no individual is any wiser than another, and no city than another. But in laying down what is or isn’t advantageous for itself, there, if anywhere, he’ll agree in turn that one counselor is superior to another, and one city’s judgment to another’s, with respect to truth. And he would hardly dare 172b to say that whatever a city lays down, thinking it advantageous for itself, will certainly turn out to its advantage. But in the area I’m speaking of, in just and unjust, pious and impious, people are willing to insist that none of these has by nature a being of its own, but that what seems so to people in common becomes true at the time it seems so, and for as long as it seems so.

TheodorusWell, don’t we have leisure, Socrates?

TheodorusWhat do you mean?

SocratesIt’s likely that those who’ve been knocking about in law courts and such places since they were young have been brought up, compared with those raised in philosophy and in 172d this kind of pursuit, like household slaves compared with free men.

TheodorusIn what way?

SocratesIn that the one sort always has what you mentioned, leisure, and they carry on their discussions in peace and at leisure. Just as we are now taking up a third argument, one after another, so do they, if the newcomer pleases them more than the one in hand, as it did us. And they don’t care whether they speak at length or briefly, if only they hit upon what is. But the others always speak with no leisure 172e (the flowing water hurries them on), and they aren’t free to make their speeches about whatever they want. The opposing party stands over them wielding compulsion, with the written charge read out alongside, beyond which nothing may be said: what they call the sworn statement. Their speeches are always about a fellow slave, addressed to a master who sits there with the case in his hand; and the contests are never about some other matter, but always about the speaker’s own case, and often the race is run 173a for his very life. As a result of all this they become tense and sharp, knowing how to flatter their master in words and fawn on him in deeds; but they’re small and crooked in their souls.note

TheodorusNot at all, Socrates; describe them. You put it very 173c well, that we who dance in this kind of chorus are not servants of our arguments; the arguments are ours, like household slaves, and each of them waits to be finished whenever we see fit. There’s no juror over us, and no spectator, as with poets, to criticize us and give orders.

SocratesLet’s talk, then, since that’s what you want, about the leaders of the chorus; for why would anyone talk about those who spend their time in philosophy in a paltry way? These people, I suppose, from their youth first of all don’t know the way to the 173d marketplace, or where the law court is, or the council chamber, or any other public meeting place of the city. Laws and decrees, spoken or written, they neither see nor hear. The eager efforts of political clubs to win office, their meetings and dinners and revels with flute-girls: it doesn’t occur to them to take part in these even in a dream. Whether someone in the city is of good or bad birth, or what flaw has come down to someone from his ancestors, on the men’s side or the women’s, he knows no more than, as the saying goes, he knows how many 173e pints there are in the sea.

TheodorusWhat do you mean, Socrates?

SocratesJust as Thales, Theodorus, while studying the stars and looking upward, fell into a well, and a witty and charming Thracian servant girl is said to have joked that he was eager to know what was in the heavens, but didn’t notice what was in front of him and at his feet. The same joke fits everyone 174b who spends his life in philosophy. For really, such a person fails to notice his neighbor, the man next door: not only what he’s doing, but almost whether he’s a human being or some other creature. But what a human being is, and what it befits such a nature to do or undergo differently from the others, that he searches for and takes pains to investigate. You understand, Theodorus, don’t you?note

TheodorusI do. And what you say is true.

SocratesThat’s why, my friend, when such a person deals 174c with anyone, privately or in public, as I was saying at the start, whenever he’s forced in a law court or anywhere else to talk about what’s at his feet and before his eyes, he gives a laugh not only to Thracian girls but to the rest of the crowd too, falling into wells and every kind of perplexity through inexperience. His awkwardness is dreadful, and gives an impression of stupidity. In exchanges of abuse he has nothing of his own to abuse anyone with, since he knows nothing bad about anyone, never having made a study of it. So, at a loss, 174d he looks ridiculous. And at people’s praises and the boasting of others he is plainly laughing, not pretending but really, and so he seems a fool.

TheodorusYou describe exactly what happens, Socrates.

SocratesBut when he himself, my friend, draws someone upward, and 175c the other is willing to step out of “What wrong am I doing you, or you me?” into an examination of justice and injustice themselves, what each of them is, and how they differ from everything else and from each other; or out of “whether a king is happy,” or “a man who has gold in store,” into an examination of kingship, and of human happiness and misery in general, what sort of things they are, and in what way it befits human nature to gain the one and escape the other: when that small-souled, sharp, litigious fellow has to 175d give an account of all these things, he pays it back in reverse. Dizzy from hanging so high, gazing down from mid-air, unused to it, distressed and at a loss and stammering, he gives a laugh, not to Thracian girls or any other uneducated person, since they don’t perceive it, but to everyone who has been brought up the opposite way from slaves.

TheodorusIf you could persuade everyone of what you say as you persuade me, Socrates, there would be more peace and fewer evils among human beings.

SocratesBut it isn’t possible for bad things to be done away with, Theodorus—there must always be something opposed to the good—nor for them to have their seat among the gods. Of necessity they haunt mortal nature and this region here. That is why we should try to flee from here 176b to there as quickly as we can. And fleeing means becoming like god so far as possible; and becoming like god means becoming just and holy, with understanding. But really, my excellent friend, it isn’t at all easy to persuade people that the reasons most of them give for fleeing wickedness and pursuing excellence are not the reasons for practicing the one and not the other. They say it’s so as not to seem bad and to seem good. That, as it seems to me, is what’s called an old wives’ tale. Let’s put the truth like this.

TheodorusWhat penalty do you mean?

SocratesThere are two patterns, my friend, set up in reality: one divine and supremely happy, the other godless and supremely wretched. Not seeing that this is so, in their foolishness and utter 177a senselessness they fail to notice that by their unjust actions they are growing like the one and unlike the other. They pay the penalty for this by living the life that matches the pattern they resemble. And if we tell them that unless they get rid of their cleverness, then when they die that place that is pure of evils will not receive them, but here on earth they will always have the kind of life that resembles them, bad men keeping company with bad—why then, being so clever and unscrupulous, they’ll listen to all this as the talk of fools.

TheodorusVery much so, Socrates.

SocratesI know it, my friend. But there’s one thing that does happen to them. When they have to give and receive an account in private about the things they disparage, and are willing to stand their ground like men for a good long while and not run away like cowards, then, strangely enough, my remarkable friend, in the end they aren’t satisfied with what they themselves are saying. That rhetoric of theirs somehow withers away, so that they seem no different from children. But let’s leave these matters, since they are really a digression—otherwise more and more 177c will keep pouring in and bury our original argument—and let’s go back to what we were discussing before, if you agree.

TheodorusFor my part, Socrates, things like this are no less pleasant to listen to; at my age they’re easier to follow. Still, if you think best, let’s go back.

SocratesWell then, we were at about this point in the argument. We were saying that those who claim that being is in motion, and that whatever seems to each person at any time also is so for the one it seems to, are willing to insist on this in other matters, and not least about what is just: 177d that whatever a city decides seems just to it and lays down, this really is just for the city that laid it down, for as long as it stays laid down. But about good things, we said, no one is any longer brave enough to dare to fight it out and claim that whatever a city lays down thinking it beneficial to itself really is beneficial, for as long as it stays laid down—unless he meant the name; and that, surely, would make a mockery of what we’re talking about. Isn’t that so?

TheodorusCertainly.

SocratesRight—he mustn’t speak of the name, but consider the thing that is named.

TheodorusNo, he mustn’t.

SocratesBut whatever the city calls it, that is surely what it aims at when it legislates, and it makes all its laws, so far as it believes and is able, as beneficial to itself as possible. Or does it legislate with an eye to something else?

TheodorusNot at all.

SocratesThen does every city always hit the mark, or does it often miss as well?

TheodorusI think they miss as well.

SocratesWell, everyone would be still more ready to agree to these same points if the question were asked about the whole class to which the beneficial belongs. And that, I take it, has to do with the time to come as well. When we legislate, we lay down laws on the understanding that they will be beneficial in the time that follows—and this we would rightly call “the future.”

TheodorusCertainly.

SocratesCome on, then, let’s put our question to Protagoras, or to anyone else who says the same as he does, like this. “A human being is the measure of all things,” as you people say, Protagoras—of white things, heavy things, light things, of every such thing without exception. For he has the standard for judging them within himself, and when he thinks they are the way he experiences them, he thinks what is true for him, and what is. Isn’t that it?

TheodorusIt is.

Socrates“And does he also have within himself the standard for the things that are going to be, Protagoras,” we’ll say, 178c “so that whatever he thinks will be actually comes about for the one who thought it? Take heat. When a layman thinks he’s going to catch a fever and that his temperature will go up, and someone else, a doctor, thinks the opposite, whose judgment shall we say the future will bear out? Or will it bear out both, so that for the doctor the man won’t become hot or feverish, but for himself he’ll be both?”

TheodorusThat would be ridiculous.

SocratesRather, I imagine, when it’s a question of whether a wine is going to be sweet or dry, 178d it’s the farmer’s judgment that carries authority, not the lyre player’s.

TheodorusOf course.

SocratesNor, again, when it’s a question of what will be out of tune or in tune, would a gymnastics trainer judge better than a musician what will later seem in tune even to the trainer himself.

TheodorusNot at all.

SocratesAnd when a feast is being prepared, the verdict of the man who is going to dine, if he knows nothing of cooking, carries less authority than the chef’s about the pleasure it will give. Let’s not yet fight it out about what is already 178e pleasant to each person, or has been. The question is about what is going to seem and to be for each person in the future: is each of us the best judge of that for himself? Or would you, Protagoras—at least about what arguments will be persuasive to each of us in a law court—judge beforehand better than any layman you like?

TheodorusVery much so, Socrates. That, at any rate, was where he emphatically promised to outdo everyone.

SocratesYes, by Zeus, my good fellow. Otherwise no one would have paid him a great deal of money 179a to talk with him, if he hadn’t persuaded his pupils that about what will be and will seem in the future, too, no seer or anyone else could judge better than he could himself.

TheodorusVery true.

SocratesThen legislation, too, and the beneficial concern the future, and everyone would agree that a city, when it legislates, must often miss what is most beneficial?

TheodorusCertainly.

SocratesThen it will be fair for us to say to your teacher 179b that he must agree that one person is wiser than another, and that such a person is a measure, while I, who don’t know, have no need whatsoever to become a measure—though the argument on his behalf was forcing me just now to be one, whether I liked it or not.

TheodorusIt seems to me, Socrates, that it’s at that point above all that the argument is caught—though it is caught here too, where it makes other people’s judgments authoritative, and those judgments turned out to hold that his own claims are not true at all.

SocratesThere are many other ways too, Theodorus, in which a claim like that could be caught, the claim that every judgment of every person is true. But where it’s a matter of each person’s present experience, from which our perceptions and the judgments that go with them arise, it’s harder to catch them out as untrue. Though perhaps I’m talking nonsense. They may well be uncatchable, and those who claim that they are self-evident and are knowledge may be telling the truth, and Theaetetus here was not wide of the mark when he 179d said that perception and knowledge are the same. So we must come to closer quarters, as the argument on Protagoras’s behalf told us to, and examine this being that is in motion, tapping it to hear whether it rings sound or cracked. There has certainly been a fight over it, and no small one, nor among only a few.

TheodorusFar from being small—in Ionia it’s even growing enormously. The followers of Heraclitus are leading the chorus for this theory with tremendous vigor.

SocratesAll the more reason, my dear Theodorus, to examine it from the 179e beginning, just as they themselves put it forward.

TheodorusAbsolutely. In fact, Socrates, as for these Heraclitean doctrines—or, as you say, Homeric, and older still—you can no more discuss them with the people around Ephesus themselves, the ones who claim to be experts, than with people driven mad by a gadfly. They are simply in motion, true to their own writings. As for sticking to an argument or a question and calmly 180a answering and asking in turn, there’s less than nothing of that in them. Or rather, “not even nothing” overstates the case, so little calm is there in these men. If you ask one of them anything, they pull out little riddling phrases as if from a quiver and shoot them off at you; and if you try to get an account of what he meant by that one, you’ll be struck by another, newly fashioned with some fresh name.

SocratesPerhaps, Theodorus, you’ve seen these men fighting but haven’t been with them in peacetime—they aren’t friends of yours. But I imagine they explain such things at their leisure to their students, whom they want to make like themselves.

TheodorusWhat students, my remarkable friend? Among people like that, nobody becomes 180c anybody’s student. They spring up on their own, wherever each one happens to have caught his inspiration, and each thinks the other knows nothing. So from these people, as I was about to say, you’ll never get an account, willingly or unwillingly. We have to take the matter over ourselves and examine it like a problem.

SocratesThat’s fair enough. And as for the problem, haven’t we inherited it from the ancients, who hid it from the many in poetry— 180d that the origin of all other things is Oceanus and Tethys, who are flowing streams, and that nothing stands still—and from later thinkers, who, being wiser, demonstrate it openly, so that even cobblers can hear and learn their wisdom, stop foolishly thinking that some things are at rest and others in motion, and, having learned that everything is in motion, hold them in honor? But I almost forgot, Theodorus, that others again have declared the opposite of this, 180e such as “Unmoved is the name for the whole,” and all the other things that the likes of Melissus and Parmenides insist on in opposition to all these: that all things are one, and that this one stands still in itself, having no place in which to move.note

TheodorusOh no, Socrates, it would be intolerable not to examine thoroughly what each side is saying.

SocratesThen we must examine it, since you’re so eager. It seems 181c to me, then, that the starting point of our inquiry is motion: what sort of thing do they mean when they say that everything is in motion? What I mean is this. Do they speak of one kind of motion, or, as it seems to me, two? But don’t let it be only my view; you take part too, so that we share whatever we have to suffer. So tell me: do you call it motion when something changes from place to place, or turns around in the same place?

TheodorusI do.

SocratesLet that be one kind, then. But when a thing stays in 181d the same place but grows old, or becomes black from white or hard from soft, or undergoes some other alteration, isn’t it right to call this another kind of motion?

TheodorusIt seems to me it has to be.

SocratesThen I say there are these two kinds of motion: alteration and movement from place to place.

TheodorusAnd you’re right.

SocratesHaving made this distinction, then, let’s now talk with those who say that everything is in motion, and ask them: “Do you say that everything 181e is in motion in both ways, both moving from place to place and altering, or that some things move in both ways and others in only one?”

TheodorusBy Zeus, I can’t say. But I think they would say in both ways.

SocratesIf not, my friend, things will turn out for them to be both in motion and at rest, and it will be no more correct to say that everything is in motion than that everything is at rest.

TheodorusVery true.

SocratesSo since they must be in motion, and there must be no absence of motion 182a in anything, all things are always in every kind of motion.

TheodorusNecessarily.

SocratesThen consider this point in their theory. Didn’t we say that they explain the coming-to-be of heat, or whiteness, or anything else, roughly like this: each of these moves, together with a perception, between what acts and what is acted on; and what is acted on becomes perceiving but not a perception, while what acts becomes something of a certain quality but not a quality? Perhaps “quality” seems a strange word to you, and you don’t understand it when it’s put so generally. So hear it 182b piece by piece. What acts doesn’t become heat or whiteness, but hot and white, and so on with the rest. You remember, I think, that earlier we said that nothing is one thing, itself by itself, and neither again is what acts or what is acted on; but that from the two of them coming together with each other, perceptions and things perceived are born, and the one side become things of a certain quality, the other perceivers.note

TheodorusI remember—of course I do.

SocratesLet’s say goodbye to the rest, then, whether they put it this way or some other. Let’s keep an eye only on the point we’re discussing, and ask: “Everything is in motion and flows, as you say? Isn’t that it?”

TheodorusYes.

SocratesWith both the motions we distinguished, moving from place to place and altering?

TheodorusOf course, if it’s to be completely in motion.

SocratesNow if things only moved from place to place and didn’t alter, we could presumably say what the things are like that flow as they move. Or how do we put it?

TheodorusLike that.

SocratesBut since not even this stays fixed—that what flows flows white—but it changes, so that there is a flowing of this very thing too, the whiteness, and a change into another color, so that it can’t be caught staying put in this respect, is it ever possible to call anything by the name of a color in such a way as to name it correctly?

TheodorusHow could anyone, Socrates? Or anything else of that sort, if it always slips away while one is speaking, flowing as it does?

SocratesAnd what shall we say about any perception whatever—for example 182e seeing or hearing? That it ever stays put in the very act of seeing or hearing?

TheodorusIt can’t, if everything is in motion.

SocratesThen we should no more call anything seeing than not seeing, nor any other perception than not, since everything is in every way in motion.

TheodorusNo, we shouldn’t.

SocratesAnd yet perception is knowledge, as Theaetetus and I said.

TheodorusYou did say that.

SocratesSo when we were asked what knowledge is, the answer we gave was no more knowledge than not knowledge.

TheodorusSo it seems.

SocratesA fine way this would turn out to correct our answer! We were so eager to show that everything is in motion, precisely so that that answer would turn out to be correct. But what has turned up, it seems, is that if everything is in motion, every answer, whatever it’s about, is equally correct—to say that it is so and that it is not so, or, if you like, that it “becomes” so, so as not to bring these people to a standstill by our words.

TheodorusYou’re right.

SocratesExcept, Theodorus, that I said “so” and “not so.” One mustn’t even say this “so”—for then 183b the “so” would no longer be in motion—nor again “not so”—for that isn’t motion either. The people who propound this theory need to establish some other language, since as things stand they have no words for their own hypothesis—unless perhaps “not even so”: that would suit them best, said with no limit.

TheodorusThat would certainly be the idiom most natural to them.

SocratesSo, Theodorus, we’re rid of your friend, and we don’t yet grant him that every man is the measure of all 183c things, unless he’s a man of understanding. And we won’t grant that knowledge is perception, at least not on the approach that everything is in motion—unless Theaetetus here has some other way of putting it.

TheodorusVery well said, Socrates. With these points settled, I too was to be released from answering you, by our agreement, once the discussion of Protagoras’s theory came to an end.

TheaetetusNot before, Theodorus, you and Socrates 183d have gone through the people who say that the whole stands still, as you proposed just now.

TheodorusTheaetetus, young as you are, are you teaching your elders to do wrong by breaking their agreements? No—get ready to give Socrates an account of what remains.

TheaetetusYes, if he wants. But I’d very much have liked to hear about the people I mean.

TheodorusWhen you challenge Socrates to argument, you’re “challenging horsemen to the plain.” So ask, and you’ll hear.note

SocratesBut I don’t think, Theodorus, I’ll do what 183e Theaetetus is asking.

TheodorusWhy won’t you do it?

SocratesMelissus and the others who say that the whole is one and stands still—I’m ashamed to examine them crudely, but I’m less ashamed before them than before Parmenides, who is one. Parmenides seems to me, in Homer’s words, “one to be revered” and at the same time “awesome.” I met the man when I was very young and he was very old, 184a and he seemed to me to have a depth that was altogether noble. So I’m afraid we may not understand what he says, and fall still further short of what he meant by it; and, most important, that the question our discussion set out to answer—what knowledge is—may go unexamined because of the arguments crowding in on us like a band of revelers, if we let them in. Besides, the argument we’re rousing now is unmanageably large. If one examines it in passing, it would be treated unworthily; and if one does it justice, it will stretch out and make the question of knowledge disappear.note

TheodorusWell, if you think so, that’s what we should do.

SocratesThen, Theaetetus, consider one more point about what’s been said. You answered that perception is knowledge, didn’t you?

TheaetetusYes.

SocratesNow suppose someone asked you: “With what does a person see white and black things, and with what does he hear high and low sounds?” You’d say, I imagine, “With the eyes and ears.”

TheaetetusI would.

SocratesBeing easygoing with words and phrases, and not scrutinizing them with precision, is for the most part not ill-bred; if anything, the opposite is small-minded. But sometimes it’s necessary—as now it’s necessary to take hold of the answer you’re giving, where it isn’t correct. Consider: which answer is more correct—that the eyes are what we see with, or what we see through; and the ears what we hear with, or what we hear through?

TheaetetusIt seems to me, Socrates, that they are what we perceive each thing through, rather than with.

SocratesYes, it would surely be strange, my boy, if a lot of senses sat inside us as if in wooden horses, and they didn’t all converge on some single form—soul, or whatever one should call it—with which we perceive, through these as instruments, everything that is perceptible.

TheaetetusWell, I think it’s this way rather than that.

SocratesHere’s why I’m being so precise with you. I want to know whether it’s with some one and the same part of ourselves that we reach white and black 184e things through the eyes, and other things again through the other senses; and whether, if asked, you’ll be able to refer all such things to the body. But perhaps it’s better for you to say these things in answering than for me to do the work on your behalf. So tell me: the things through which you perceive what is hot and hard and light and sweet—do you count each of them as belonging to the body, or to something else?

TheaetetusTo nothing else.

SocratesAnd will you also be willing to agree that what you perceive through one power 185a it is impossible to perceive through another—for example, what you perceive through hearing, to perceive through sight, or what through sight, through hearing?

TheaetetusOf course I’ll be willing.

SocratesSo if you think something about both, you couldn’t be perceiving it about both through either the one organ or the other.

TheaetetusNo, I couldn’t.

SocratesNow take a sound and a color. First of all, don’t you think this very thing about both of them, that both of them are?

TheaetetusI do.

SocratesAnd also that each of them is different from the other and the same as itself?

TheaetetusOf course.

SocratesAnd that both together are two, and each is one?

TheaetetusThat too.

SocratesAnd are you also able to consider whether they are unlike or like each other?

TheaetetusPerhaps.

SocratesNow through what do you think all these things about them? It’s not possible to grasp what they have in common either through hearing or through sight. Here’s further evidence for what we’re saying. If it were possible to consider whether both are salty or not, 185c you know you’ll be able to say what you would consider it with; and that is clearly neither sight nor hearing, but something else.

TheaetetusOf course it is—the power that works through the tongue.

SocratesWell said. But through what does the power work that makes plain to you what is common to all things, and to these in particular—what you apply the words “is” and “is not” to, and the other things we were just asking about them? What organs will you assign to all these, through which the perceiving part of us perceives each of them?

TheaetetusYou mean being and not-being, likeness and unlikeness, the same and the different, and also 185d one and the rest of number as applied to them. And clearly you’re also asking about even and odd, and everything else that goes with these—through which of the body’s parts do we perceive them with the soul?

SocratesYou’re following me splendidly, Theaetetus. Those are exactly the things I’m asking about.

TheaetetusBy Zeus, Socrates, I couldn’t say—except that it seems to me there isn’t any special organ for these things at all, as there is for the others. Rather, 185e it seems to me that the soul itself, through itself, examines what is common to all things.

SocratesThat’s because you’re beautiful, Theaetetus, and not ugly, as Theodorus was saying—for whoever speaks beautifully is beautiful and good. And besides being beautiful, you’ve done me a kindness: you’ve released me from a very long argument, if it seems to you that the soul examines some things itself through itself, and others through the body’s powers. That was what I thought myself, and I wanted you to think so too.note

TheaetetusWell, it certainly does seem so.

SocratesTo which of the two, then, do you assign being? For this, above all, goes along with everything.

TheaetetusI assign it to the things the soul reaches out for itself, by itself.

SocratesAnd like and unlike too, and same and different?

TheaetetusYes.

SocratesWhat about beautiful and ugly, good and bad?

TheaetetusThese too, I think, are among the things whose being it examines most of all in relation to one another, weighing up within itself the 186b past and the present against the future.

SocratesHold on. Won’t it perceive the hardness of what is hard through touch, and the softness of what is soft in the same way?

TheaetetusYes.

SocratesBut their being, and the fact that they are, and their opposition to each other, and again the being of that opposition—these the soul itself tries to judge for us, by going back over them and comparing them with one another.

TheaetetusCertainly.

SocratesSo there are some things that humans and animals alike are naturally able to perceive 186c from the moment they’re born: the experiences that reach the soul through the body. But reflections on these, as regards their being and usefulness, come only with difficulty and over time, through a great deal of trouble and education, to those they come to at all?

TheaetetusAbsolutely.

SocratesNow can someone reach truth who doesn’t even reach being?

TheaetetusImpossible.

SocratesAnd if someone fails to reach the truth of something, will he ever have knowledge of it?

TheaetetusHow could he, Socrates?

SocratesSo knowledge is not in our experiences but in our reasoning about them. For in reasoning, it seems, it is possible to grasp being and truth, but in experiences it’s impossible.

TheaetetusApparently.

SocratesThen will you call the two by the same name, when they differ so greatly?

TheaetetusThat wouldn’t be right, anyway.

SocratesThen what name do you give to the first—seeing, hearing, smelling, feeling cold, feeling hot?

TheaetetusPerceiving. What else?

SocratesSo all of it together you call perception?

TheaetetusNecessarily.

SocratesWhich, we say, has no share in grasping truth—since it has none in grasping being either.

TheaetetusNo, it hasn’t.

SocratesNor, then, in knowledge.

TheaetetusNo.

SocratesThen perception and knowledge could never be the same thing, Theaetetus.

TheaetetusApparently not, Socrates. And now, above all, it has become perfectly plain that knowledge is something other than perception.

SocratesBut we certainly didn’t begin our conversation in order to find out what knowledge is not, but what it is. Still, we’ve come this far: we won’t look for it in perception at all, but in whatever name the soul has when it is occupied, itself by itself, with the things that are.

TheaetetusWell, Socrates, that, I think, is called judging.

SocratesYou think rightly, my friend. Now look again from the 187b beginning. Wipe out everything that came before and see whether you can see any better, now that you’ve come this far. And tell me again what knowledge is.

TheaetetusIt’s impossible to say it’s judgment of every kind, Socrates, since there is false judgment too. But it looks as if true judgment is knowledge; let that be my answer. If it doesn’t turn out that way as we go on, as happened this time, we’ll try to say something else.

SocratesThat’s the way to speak, Theaetetus—eagerly, rather than the way you hesitated to answer at first. For if 187c we act like this, one of two things will happen: either we’ll find what we’re after, or we’ll be less inclined to think we know what we don’t know at all—and that would be no contemptible reward. So what do you say now? There being two kinds of judgment, one true and the other false, do you define knowledge as true judgment?

TheaetetusI do. That, in turn, is how it looks to me now.

SocratesThen is it still worth going back over something about judgment—

TheaetetusWhat do you mean?

SocratesSomething troubles me—now, and often before too—so that I’ve been in great perplexity, both by myself and with others, unable to say what this experience in us is and how it comes about.

TheaetetusWhat experience?

SocratesSomeone’s judging falsely. Even now I’m still in two minds, considering whether we should let it go, or examine it in a different way from a little while ago.

TheaetetusWhy not, Socrates, if it seems in any way necessary? Just now you and Theodorus were saying, and rightly, about leisure, that in discussions like these nothing presses us.

SocratesYou’re right to remind me. Perhaps it’s not a bad moment to go back over our tracks, as it were. It’s surely better to get through a little well than a lot inadequately.

TheaetetusOf course.

SocratesWell then, what are we actually saying? Do we say that there is false judgment on each occasion, and that one of us judges falsely and another truly, as if that were how things naturally are?

TheaetetusYes, we do.

SocratesNow isn’t it true for us, about all things together and each in particular, that either we know it or we don’t know it? Learning and forgetting, as things in between, I’ll leave aside for now; they have nothing to do with our argument at present.

TheaetetusWell, Socrates, there’s nothing else left about each thing except knowing it or not knowing it.

SocratesThen it follows that anyone who judges must judge either something he knows or something he doesn’t know?

TheaetetusIt must.

SocratesAnd it’s certainly impossible for someone who knows a thing not to know it, or for someone who doesn’t know it 188b to know it.

TheaetetusOf course.

SocratesThen does someone who judges falsely think that things he knows are not those things but some others of the things he knows—so that, knowing both, he is also ignorant of both?

TheaetetusThat’s impossible, Socrates.

SocratesWell then, does he think that things he doesn’t know are some others of the things he doesn’t know? Is it possible for someone who knows neither Theaetetus nor Socrates to get it into his head that Socrates is Theaetetus, or Theaetetus Socrates?

TheaetetusHow could he?

SocratesBut surely a person doesn’t think that things he knows are things he doesn’t know, or again that things he doesn’t know are things he knows.

TheaetetusThat would be monstrous.

SocratesThen how could anyone still judge falsely? Outside these cases, surely, it is impossible to judge, since everything is either known or not known by us; and within them it appears nowhere possible to judge falsely.

TheaetetusVery true.

SocratesThen shouldn’t we look for what we’re seeking not this way, going by 188d knowing and not knowing, but by being and not being?

TheaetetusWhat do you mean?

SocratesIt may simply be that someone who judges about anything things that are not cannot fail to judge falsely, however things stand with his thinking otherwise.

TheaetetusThat’s likely too, Socrates.

SocratesWell then, what shall we say, Theaetetus, if someone cross-examines us: “Is what you describe possible for anyone? Will any human being judge what is not, whether about one of the things that are or just by itself?” And we, it seems, will reply: “Yes, when 188e he thinks, but thinks what is not true.” Or what shall we say?

TheaetetusThat.

SocratesThen is there something like this anywhere else too?

TheaetetusLike what?

SocratesSomeone’s seeing something, yet seeing nothing.

TheaetetusHow could that be?

SocratesBut surely if he sees some one thing, he sees one of the things that are. Or do you think that what is one can ever be among the things that are not?

TheaetetusI don’t.

SocratesSo whoever sees some one thing sees something that is.

TheaetetusApparently.

SocratesAnd whoever hears something hears some one thing, and something that is.

TheaetetusYes.

SocratesAnd whoever touches something touches some one thing, and something that is, if it’s one?

TheaetetusThat too.

SocratesAnd doesn’t whoever judges judge some one thing?

TheaetetusHe must.

SocratesAnd whoever judges some one thing judges something that is?

TheaetetusI agree.

SocratesSo whoever judges what is not judges nothing.

TheaetetusApparently.

SocratesBut whoever judges nothing doesn’t judge at all.

TheaetetusThat seems clear.

SocratesSo it isn’t possible to judge what is not, either about the things that are or just by itself.

TheaetetusApparently not.

SocratesSo judging falsely is something other than judging things that are not.

TheaetetusIt seems to be something other.

SocratesSo neither this way nor the way we were examining it a little while ago is there false judgment in us.

TheaetetusNo, there isn’t.

SocratesWell, is it when it happens like this that we give it that name?

TheaetetusHow?

SocratesWe say that false judgment is a kind of other-judging, 189c when someone, having swapped one of the things that are for another of the things that are in his thinking, says that it is that other. For in this way he always judges something that is, but one thing in place of another; and since he misses what he was aiming at, he could fairly be called someone who judges falsely.

TheaetetusNow I think you’ve put it exactly right. When someone judges ugly in place of beautiful, or beautiful in place of ugly, then he truly judges falsely.

SocratesIt’s obvious, Theaetetus, that you look down on me and aren’t afraid of me.

TheaetetusWhy do you say that?

SocratesYou don’t think, I imagine, that I’d pounce on your “truly falsely” 189d and ask whether it’s possible for what is swift to come about slowly, or what is light heavily, or for any other opposite to come about, not according to its own nature but according to that of its opposite, in a way opposite to itself. I’ll let that pass, then, so that your boldness won’t go for nothing. But you’re satisfied, you say, that judging falsely is other-judging?

TheaetetusI am.

SocratesSo in your judgment it is possible to set down in one’s thinking one thing as another and not as what it is.

TheaetetusYes, it is.

SocratesNow when someone’s thinking does this, mustn’t it be thinking either of both things or of one of them?

TheaetetusYes, it must—either both at once or in turn.

SocratesExcellent. And by thinking do you mean what I mean?

TheaetetusWhat do you mean by it?

SocratesAn account that the soul goes through with itself about whatever it’s considering. I’m telling you this, mind you, as someone who doesn’t know. But this is the picture I have of it: when the soul thinks, it is simply conversing, 190a asking itself questions and answering them, saying yes and saying no. And when it has come to a decision, whether slowly or with a sudden leap, and is now saying the same thing and not in two minds, we call this its judgment. So what I call judging is speaking, and a judgment is a statement that has been made—not to someone else, though, and not aloud, but silently to oneself. What about you?

TheaetetusI call it that too.

SocratesSo when someone judges one thing to be another, it seems he is also saying to himself that the one thing is the other.

TheaetetusOf course.

SocratesNow try to remember whether you’ve ever said to yourself that beyond all doubt what is beautiful is ugly, or what is unjust is just. Or—to sum it all up—consider whether you’ve ever tried to persuade yourself that beyond all doubt one thing is another. Isn’t it quite the reverse? Not even in your sleep have you ever dared to say to yourself that odd numbers are, after all, completely even, or anything else of that sort.

TheaetetusThat’s true.

SocratesAnd do you think anyone else, sane or mad, would dare to say to himself in earnest, trying to talk himself into it, that the ox must be a horse, or two must be one?

TheaetetusBy Zeus, I don’t.

SocratesSo if speaking to oneself is judging, no one who speaks of both things and judges both, grasping both with his soul, could say and judge that the one is the other. But you too must let the word “other” pass; 190d what I mean by it is this: that no one judges that the ugly is beautiful, or anything else of that sort.

TheaetetusYes, Socrates, I’ll let it pass, and I think it’s as you say.

SocratesSo it is impossible for someone who is judging both things to judge that the one is the other.

TheaetetusIt seems so.

SocratesBut then if he judges only one of them, and not the other at all, he will never judge that the one is the other.

TheaetetusTrue. He’d be forced to grasp the one he isn’t judging too.

SocratesSo neither someone who judges both nor someone who judges one of them can 190e other-judge. And so anyone who defines false judgment as other-judging would be talking nonsense. Neither this way nor the earlier ways does false judgment appear to exist in us.

TheaetetusIt seems not.

SocratesAnd yet, Theaetetus, if it turns out that this doesn’t exist, we’ll be forced to agree to many absurd things.

TheaetetusWhat sort of things?

SocratesI won’t tell you until I’ve tried examining it in every way. I’d be ashamed on our behalf if, while we’re still at a loss, we were forced 191a to agree to what I have in mind. But if we find the answer and get free, then we’ll talk about other people as the ones this happens to, while we stand clear of the ridicule. And if we’re completely at a loss, then I suppose we’ll be humbled, and like seasick passengers we’ll let the argument trample on us and do whatever it likes with us. So listen to where I still find a way through our problem.

TheaetetusJust tell me.

SocratesI’ll deny that we were right to agree, when we agreed that it’s impossible for someone to judge that things he knows are things he doesn’t know, 191b and to be deceived. It is possible, in a way.

TheaetetusDo you mean what I suspected myself at the time we said it was like this: that sometimes I, who know Socrates, see someone else in the distance whom I don’t know, and think it is Socrates, whom I know? That sort of thing you’re talking about does happen in a case like that.

SocratesAnd didn’t we back away from that, because it made us both know and not know what we know?

TheaetetusCertainly.

SocratesLet’s not put it that way, then, but like this. Perhaps it will 191c give way to us, perhaps it will resist. But really we’re in such a tight spot that we have to turn every argument over and put it to the test. So see whether I’m talking sense. Is it possible for someone who didn’t know something before to learn it later?

TheaetetusYes, it is.

SocratesAnd again another thing, and another?

TheaetetusOf course.

TheaetetusI’ll suppose it.

SocratesLet’s say, then, that it is a gift from Memory, the mother of the Muses, and that whenever we want to remember something we see or hear or think of ourselves, we hold this block under our perceptions and thoughts and take an imprint of it, as if we were stamping the marks of signet rings. Whatever is imprinted, we remember and know for as long as its image is there; whatever is wiped out, or can’t 191e be imprinted, we have forgotten and don’t know.note

TheaetetusLet it be so.

SocratesNow take someone who knows these things and is considering something he is seeing or hearing. Look and see whether he might judge falsely in the following way.

TheaetetusWhat way?

SocratesBy thinking that things he knows are sometimes things he knows, and sometimes things he doesn’t. In our earlier discussion we were wrong to agree that these things are impossible.

TheaetetusAnd what do you say now?

SocratesWe must put it like this, drawing our distinctions from the beginning. Take something a person knows, having a record of it in his soul, but isn’t perceiving: it is impossible for him to think it is some other thing he knows, of which he also has an imprint but which he isn’t perceiving. And to think that something he knows is something he doesn’t know and has no seal-impression of; and that something he doesn’t know is something else he doesn’t know; and that something he doesn’t know is something he knows. And to think that something he is perceiving is some other thing he is perceiving; and that something he is perceiving is something he isn’t perceiving; and 192b that something he isn’t perceiving is something else he isn’t perceiving; and that something he isn’t perceiving is something he is perceiving.

TheaetetusIn which cases? Maybe I’ll understand better from them; at the moment I can’t follow.

SocratesIn cases where he thinks that things he knows are some other things that he knows and is perceiving; or that he doesn’t know but is perceiving; or that things 192d he knows and is perceiving are other things that, again, he knows and is perceiving.

TheaetetusNow I’m left much further behind than before.

SocratesThen listen to it again, this way. I know Theodorus, and remember within myself what he is like, and Theaetetus in the same way. Don’t I sometimes see them and sometimes not; sometimes touch them and sometimes not; and hear them or perceive them by some other sense, and at other times have no perception of the two of you at all, but remember you nonetheless and know you within myself?

TheaetetusCertainly.

SocratesThen here is the first of the things I want to make clear—learn this: that it is possible not to perceive things one knows, and possible to perceive them.

TheaetetusTrue.

SocratesAnd things one doesn’t know, often it is possible not to perceive them either, and often possible only to perceive them?

TheaetetusThat’s possible too.

SocratesSee, then, whether you can follow better now. If Socrates 193a knows Theodorus and Theaetetus, but sees neither of them and has no other perception of them either, he could never judge within himself that Theaetetus is Theodorus. Am I talking sense or not?

TheaetetusYes, that’s true.

SocratesWell, that was the first of the cases I was describing.

TheaetetusYes, it was.

SocratesThe second, then: if I know one of you and don’t know the other, and perceive neither, I could never think that the one I know is the one I don’t know.

TheaetetusRight.

SocratesAnd the third: if I neither know nor perceive either of you, I could not think that the one I don’t know is some other person I don’t know. And imagine you’ve heard all the other earlier cases again in order, in which I will never judge falsely about you and Theodorus, whether I know both of you or neither, or know one and not the other. And the same goes for the cases involving perception, if you’re following.

TheaetetusI’m following.

SocratesThen the only place left for judging falsely is here. Suppose I know you and Theodorus, and I have the marks of you both in that wax block, 193c like the imprints of signet rings. I see you both from a distance, and not clearly enough, and I’m eager to assign the proper mark of each to the proper sight, fitting the sight into its own track so that recognition can take place. Then I fail at this: like people who put their shoes on the wrong feet, I switch them round and apply the sight of each of you to the other’s mark. Or else the same thing happens to me as happens to sight in mirrors, when right flows over into 193d left, and I go wrong. That’s when mistaking one thing for another, and judging falsely, comes about.

TheaetetusYes, it seems so, Socrates. It’s wonderful how well you describe what happens to judgment.

SocratesThen there’s also the case where I know you both, and besides knowing one of you I perceive him, but not the other, and the knowledge I have of the other isn’t matched with my perception. That’s what I was describing earlier, and you didn’t understand me then.

TheaetetusNo, I didn’t.

SocratesWell, what I was saying was this: if someone knows one person and 193e perceives him, and has his knowledge of him matched with his perception of him, he will never think that person is someone else whom he knows and perceives and whose knowledge he likewise has matched with his perception. Wasn’t that it?

TheaetetusYes.

SocratesWhat was left out, I think, is the case we’re describing now, where we say false judgment arises: someone knows both people and sees both, 194a or has some other perception of both, but doesn’t hold each of the two marks up against the perception that belongs to it. Like a poor archer, he shoots wide of the target and misses—and that, of course, is just what we’ve named falsehood.

TheaetetusReasonably enough.

SocratesAnd when perception is present for one of the marks but not for the other, and the mind fits the mark belonging to the absent perception to the present one, in every such case the mind is deceived. In a word: about things a person doesn’t know and has never perceived, it seems there can be no 194b being deceived and no false judgment, if what we’re saying now makes any sense. It’s about the very things we know and perceive that judgment twists and turns, becoming false or true. When it brings the proper stamps and imprints together squarely and directly, it’s true; when it brings them together askew and crooked, it’s false.

TheaetetusWell, isn’t that finely put, Socrates?

SocratesYou’ll say so all the more when you’ve heard this too. Judging truly is a fine thing, and being deceived a shameful one.

TheaetetusOf course.

SocratesWell, they say these come about like this. When the wax in someone’s soul is deep, plentiful, smooth, and worked to just the right softness, the things that come in through the perceptions are stamped on this “heart” of the soul—Homer’s word, hinting at its likeness to wax. In people like that 194d the marks that form are clean and deep enough, and they last a long time. Such people are, first, quick to learn; second, good at remembering; and third, they don’t mismatch the marks of their perceptions, but judge truly. Since the marks are clear and have plenty of room, they quickly assign each thing to its own imprint—to what are called the things that are—and these people are called wise. Don’t you think so?note

TheaetetusExtraordinarily so.

SocratesNow when someone’s heart is “shaggy”—the thing the all-wise poet praised—or dirty, of impure wax, or very soft or hard: those with soft wax are quick to learn but forgetful, and those with hard wax the opposite. Those whose wax is shaggy and rough, something stony, full of earth or dirt mixed in, get unclear imprints. So do those with hard wax, since there’s no depth in it. And those with soft wax get 195a unclear imprints too, because they quickly run together and blur. And if, on top of all this, the imprints are crowded on top of one another for lack of room, because someone’s little soul is small, they’re even less clear than those. So all these people turn out to be the sort who judge falsely.note

TheaetetusNobody could put it more rightly, Socrates.

SocratesShall we say, then, that there are false judgments in us?

TheaetetusVery much so.

SocratesAnd true ones too?

TheaetetusTrue ones too.

SocratesSo do we now think it’s been adequately agreed that both these kinds of judgment certainly exist?

TheaetetusEmphatically.

SocratesTheaetetus, a man who babbles really is a terrible and tiresome thing, it seems.

TheaetetusWhat? What made you say that?

SocratesI’m annoyed at my own slowness—and at what really is babbling. What else would you call it when someone drags arguments up and down because he’s too dull to be convinced, and can’t bear to let go of any of them?

TheaetetusBut what are you annoyed about?

SocratesI’m not just annoyed; I’m also afraid of what I’ll answer if someone asks me: “Socrates, so you’ve discovered false judgment: it’s not in perceptions in relation to each other, nor 195d in thoughts, but in the fitting of perception to thought?” I expect I’ll say yes, preening myself as though we’d discovered something fine.

TheaetetusIt seems to me, Socrates, that what we’ve just shown is nothing to be ashamed of.

Socrates“Then,” he’ll say, “you’re claiming that we could never think a man we’re only thinking of, and not seeing, is a horse, which again we neither see nor touch but only think of, without perceiving anything else about it?” I expect I’ll say that’s what I mean.

TheaetetusAnd rightly.

Socrates“Well then,” he’ll say, “by this argument, wouldn’t it follow that someone could never think that eleven, which he does nothing but think of, is twelve, which again he only thinks of?” Come on, then—you answer.

TheaetetusWell, I’ll answer that someone who sees or touches eleven things might think they’re twelve, but that about the eleven and twelve he has in his thought he could never judge that.

SocratesReally? Take five and 196a seven. Do you think anyone has ever considered, in his own mind—I don’t mean setting out seven men and five to look at, or anything like that, but five and seven themselves, which we say are records there in the wax block, about which there can be no false judgment—has anyone ever considered these very things, talking to himself and asking how many they are, and one person thought and said they were eleven, and another twelve? Or does everyone say and think they’re twelve?

TheaetetusNo, by Zeus. Plenty say eleven. And if you consider it with larger numbers, people go wrong more often. I take it you’re talking about numbers in general.

SocratesYou take it rightly. And consider whether what happens then is anything other than thinking that the twelve itself, the one in the wax block, is eleven.

TheaetetusIt seems so.

SocratesThen doesn’t that bring us back to our first arguments? Anyone to whom this happens thinks that something he knows is another of the things he knows, which we said was impossible. And that was exactly how we were forced to say that there’s no 196c false judgment: so that the same person wouldn’t be forced to know and not know the same things at the same time.

TheaetetusVery true.

SocratesThen we have to show that judging falsely is something other than a mismatch of thought with perception. If that were what it was, we’d never be deceived in our thoughts by themselves. As things stand, either there’s no false judgment, or it’s possible not to know what one knows. Which of these do you choose?

TheaetetusThat’s no choice at all, Socrates.

SocratesAnd yet the argument will probably not allow both. Still—since we must dare everything—what if we tried being shameless?

TheaetetusHow?

SocratesBy being willing to say what knowing is like.

TheaetetusAnd what’s shameless about that?

SocratesYou don’t seem to realize that our whole discussion from the start has been a search for knowledge, on the assumption that we don’t know what it is.

TheaetetusNo, I do realize it.

SocratesThen don’t you think it’s shameless, when we don’t know what knowledge is, to declare what knowing is like? But in fact, 196e Theaetetus, we’ve been infected all along with an impure way of talking. Countless times we’ve said “we know” and “we don’t know,” “we have knowledge” and “we don’t have knowledge,” as if we understood each other at all while we’re still ignorant of knowledge. And, if you like, even at this very moment we’ve used “be ignorant” and “understand” again, as if it were proper for us to use them when we lack knowledge.

TheaetetusBut how will you carry on a discussion, Socrates, if you keep away from these words?

SocratesNot at all, being the man I am—though I could if I were an expert in contradiction. If a man like that were here now, he’d tell us to keep away from them, and he’d come down hard on us for the things I’m saying. But since we’re no good at it, do you want me to be bold and say what knowing is like? I think it might be of some use.

TheaetetusBe bold, then, by Zeus. You’ll be fully forgiven for not keeping away from those words.

SocratesWell, have you heard what people nowadays say knowing is?

TheaetetusPerhaps; but I don’t remember at the moment.

SocratesThey say, I think, that it’s the having of knowledge.

TheaetetusThat’s true.

SocratesWell, let’s make a small change and say it’s the possession of knowledge.

TheaetetusAnd how will you say that differs from the other?

SocratesPerhaps not at all. But hear what I think and help me test it.

TheaetetusIf I can.

SocratesWell, to me possessing doesn’t look the same as having. For example, if someone bought a cloak and it was his to use but he wasn’t wearing it, we wouldn’t say he had it, though we would say he possessed it.

TheaetetusRightly.

TheaetetusYes.

SocratesBut in another sense he has none of them. Rather, he’s acquired a power over them, since he’s brought them under his control in an enclosure of his own: he can take them and hold them whenever 197d he wants, catching whichever one he likes, and let them go again, and he’s free to do this as often as he sees fit.

TheaetetusThat’s so.

SocratesOnce again, then: just as before we built a wax model of some kind in our souls—I don’t know what— let’s now make in each soul a kind of aviary of all sorts of birds, some in flocks apart from the others, some in small groups, and some alone, flying among all the rest wherever they happen to go.

TheaetetusConsider it made. But what next?

SocratesWe must say that while we’re children this container is empty, and think of pieces of knowledge in place of the birds. Whatever piece of knowledge someone acquires and shuts up in the enclosure, we must say he has learned or discovered the thing this knowledge was of, and that this is what knowing is.

TheaetetusLet’s say so.

SocratesNow consider what words are needed for hunting again for whichever piece of knowledge he wants, taking and holding it, and letting it go again—whether the same ones as when he first acquired it, or different ones. You’ll understand what I mean more clearly from this. You call arithmetic an art, don’t you?

TheaetetusYes.

SocratesThen take it to be a hunt for pieces of knowledge of everything odd and even.

TheaetetusI take it that way.

SocratesAnd it’s by this art, I think, that someone both has the 198b pieces of knowledge of numbers under his control himself, and hands them on to someone else, if he hands them on.

TheaetetusYes.

SocratesAnd we call handing them on “teaching,” taking them over “learning,” and having them, by possessing them in that aviary, “knowing.”

TheaetetusCertainly.

SocratesNow pay attention to what follows. The complete arithmetician knows all numbers, doesn’t he? He has pieces of knowledge of all numbers in his soul.

TheaetetusOf course.

SocratesThen would such a person ever count anything—either numbers themselves, to himself, or some external thing that has number?

TheaetetusOf course he would.

SocratesAnd we’ll say that counting is nothing other than examining how large some number happens to be.

TheaetetusYes.

SocratesThen it appears that the man we agreed knows every number is examining what he knows as if he didn’t know it. I’m sure you’ve heard such puzzles argued.

TheaetetusI have.

SocratesSo, drawing our likeness from the possessing and hunting of pigeons, we’ll say the hunting was of two kinds: one before possession, for the sake of possessing; the other, once one possesses them, to take and hold in one’s hands what one possessed long ago. In the same way, with things he had pieces of knowledge of long ago, having learned them, and knew—isn’t it possible to learn these very same things again, by taking up the knowledge of each and holding it, knowledge he possessed long ago but didn’t have ready to hand in his thought?

TheaetetusTrue.

SocratesThat’s just what I was asking a moment ago: how should we use our words in speaking of this, when the arithmetician sets out to count or the man who knows his letters to read something? Should we say that in such a case, although he knows, he comes to learn again from himself what he knows?

TheaetetusBut that’s absurd, Socrates.

SocratesThen should we say he’ll read 199a and count what he doesn’t know, when we’ve granted that he knows all the letters and every number?

TheaetetusThat’s unreasonable too.

SocratesThen do you want us to say that we don’t care about the words—let anyone drag “knowing” and “learning” wherever he likes—but since we’ve defined possessing knowledge as one thing and having it as another, we say it’s impossible for someone not to possess what he possesses, so that it never happens that someone doesn’t know what he knows, and yet it is possible to get a false judgment about it?

For it’s possible not to have the knowledge of that thing but another instead of it: when, hunting for some piece of knowledge as they fly about, he misses and takes one instead of another. That’s when he thought eleven was twelve: he took the knowledge of eleven instead of the knowledge of twelve, the one inside him—a ring dove, as it were, instead of a pigeon.

TheaetetusYes, that makes sense.

SocratesBut when he takes the one he’s trying to take, then he’s free of deception and judges what is. And so there is both true and 199c false judgment, and none of the things that troubled us earlier stands in the way? Perhaps you’ll agree with me. Or what will you do?

TheaetetusI agree.

SocratesYes, we’re rid of the business of people not knowing what they know; for it no longer turns out anywhere that we don’t possess what we possess, whether we’re deceived about something or not. But I think another, stranger difficulty is coming into view.

TheaetetusWhat’s that?

SocratesWhether a swap of pieces of knowledge could ever turn out to be false judgment.

TheaetetusHow do you mean?

SocratesFirst, that someone who has knowledge of something should be ignorant of that very thing—not through lack of knowledge but through his own knowledge. Then, that he should judge this thing to be that, and that to be this. Isn’t it utterly unreasonable that when knowledge comes to it the soul should recognize nothing and be ignorant of everything? By this argument nothing stops ignorance, when it comes, from making someone know something, and blindness from making him see—if knowledge is ever going to make someone ignorant.

TheaetetusPerhaps, Socrates, we weren’t right to make the birds only pieces of knowledge. We should have put pieces of ignorance in the soul too, flying about along with them. Then the hunter, catching now a piece of knowledge and now a piece of ignorance of the same thing, judges falsely by the ignorance and truly by the knowledge.

SocratesIt’s not easy not to praise you, Theaetetus. But look again at what you said. Let it be as you say: then the man who catches the 200a piece of ignorance will judge falsely, you say. Right?

TheaetetusYes.

SocratesBut surely he won’t also believe he’s judging falsely.

TheaetetusOf course not.

SocratesNo—truly; and he’ll be in the frame of mind of someone who knows about the things he’s deceived about.

TheaetetusCertainly.

SocratesSo he’ll think he’s caught and has a piece of knowledge, not a piece of ignorance.

TheaetetusClearly.

SocratesSo after going a long way round we’re back at our first puzzle. That expert in refutation will laugh and say: 200b “My excellent friends, does someone who knows both, a piece of knowledge and a piece of ignorance, think the one he knows is another of the ones he knows? Or, knowing neither, does he judge the one he doesn’t know to be another of the ones he doesn’t know? Or, knowing one and not the other, does he judge the one he knows to be the one he doesn’t? Or believe the one he doesn’t know is the one he knows? Or will you tell me again that there are pieces of knowledge of the pieces of knowledge and ignorance, which their possessor has shut up in some other ridiculous 200c aviaries or wax models, and knows as long as he possesses them, even if he doesn’t have them ready to hand in his soul? Will you be forced in this way to keep running round to the same place countless times and get nowhere?” What shall we answer to that, Theaetetus?

TheaetetusBy Zeus, Socrates, I don’t know what to say.

SocratesWell then, my boy, isn’t the argument right to rebuke us, and to point out that we’re wrong to look for false judgment before 200d knowledge, and let knowledge go? It’s impossible to understand false judgment until one has adequately grasped what knowledge is.

TheaetetusAs things stand, Socrates, I have to think it’s as you say.

SocratesThen what will someone say knowledge is, starting again from the beginning? Surely we’re not going to give up yet?

TheaetetusNot at all—unless you give up.

SocratesTell me, then: what could we say it is that would least contradict ourselves?

TheaetetusWhat we tried before, Socrates. I don’t have anything else.

SocratesWhat was that?

TheaetetusThat true judgment is knowledge. Judging truly is surely free of error, and everything that comes of it turns out fine and good.

SocratesThe man leading the way across the river, Theaetetus, said, “It will show you.” So with this: if we go on and search into it, it may turn up 201a in our path and reveal what we’re looking for; if we stay put, nothing will become clear.note

TheaetetusYou’re right. Let’s go on and examine it.

SocratesWell, this won’t take long to examine. There’s a whole art that tells you it isn’t knowledge.

TheaetetusHow so? What art is that?

SocratesThe art of the greatest in wisdom—the people called orators and lawyers. They persuade by their art, I think, not by teaching but by making people judge whatever they want. Or do you think there are teachers so clever 201b that, in the little time the water clock allows, they can adequately teach the truth of what happened to people who weren’t there when others were robbed of money or suffered some other violence?

TheaetetusI don’t think so at all; but they can persuade them.

SocratesAnd by “persuade” don’t you mean “make them judge”?

TheaetetusOf course.

SocratesThen when jurors are justly persuaded about things only an eyewitness can know, and no one else, then, judging these things from 201c hearsay and getting a true judgment, they’ve judged without knowledge, though they were rightly persuaded, if they gave a good verdict?

TheaetetusAbsolutely.

SocratesBut, my friend, if true judgment and knowledge were the same, even in the law courts, the best of jurors would never judge correctly without knowledge. As it is, they seem to be two different things.

TheaetetusYes, Socrates—I’d forgotten it, but I heard someone say this, and now I’m thinking of it. He said that true judgment with an account 201d is knowledge, and that true judgment without an account falls outside knowledge. And things of which there is no account are not knowable—that was the very word he used—while those that have one are knowable.

SocratesThat’s well said. But tell me how he distinguished these knowable and unknowable things, so we can see whether you and I have heard the same version.

TheaetetusI don’t know whether I’ll be able to work it out; but if someone else stated it, I think I could follow.

SocratesThen listen to a dream in return for a dream. I too seemed 201e to hear some people say that the first elements, as it were, of which we and everything else are composed, have no account. Each of them, itself by itself, can only be named; nothing else can be said of it, neither that it is nor that it is not, for then being or not-being would 202a already be attached to it, whereas nothing must be added if one is to speak of that thing alone. Not even “itself” or “that” or “each” or “alone” or “this” should be added, nor many other such words. For these run around and attach to everything, being different from the things they’re added to; whereas if it were possible to express the element itself, and it had an account all its own, it would have to be expressed without all the others.note

TheaetetusExactly like that.

SocratesSo you’re satisfied, and you put it this way: that true judgment with an account is knowledge?

TheaetetusAbsolutely.

SocratesHave we, Theaetetus, now, on this very day, caught what many wise men have long been searching for and grown old before finding?

TheaetetusIt seems to me, at any rate, Socrates, that what’s just been said is well said.

SocratesAnd it’s likely that this very thing is so; for what knowledge could there still be apart from an account and correct judgment? But one of the things that were said displeases me.