Theaetetus! (Synopsis – highlights & unredacted quotes lifted from the Socratic dialogue by Plato, Benjamin Jowett translation)

Themes: On what knowledge is or rather is not, On the difference between a philosopher and a lawyer, On theories of mind, On the doctrine of perpetual flux, On the existence/non-existence of false opinion.

’Is not learning growing wiser about that which you learn?’ …  And by wisdom the wise are wise? …  And is that different in any way from knowledge? 

Herein lies the difficulty which I can never solve to my satisfaction–What is knowledge? Can we answer that question? 

Theaetetus attempts at giving the definition of knowledge:

1. I think that the sciences which I learn from Theodorus— geometry, and those which you just now mentioned–are knowledge; and I would include the art of the cobbler and other craftsmen; these, each and all of, them, are knowledge. 
   • But that, Theaetetus, was not the point of my question: we wanted to know not the subjects, nor yet the number of the arts or sciences, for we were not going to count them, but we wanted to know the nature of knowledge in the abstract. Am I not right? 
   • How can a man understand the name of anything, when he does not know the nature of it? … And when a man is asked what science or knowledge is, to give in answer the name of some art or science is ridiculous; for the question is, ‘What is knowledge?’ and he replies, ‘A knowledge of this or that.’ … Moreover, he might answer shortly and simply, but he makes an enormous circuit. For example, when asked about the clay, he might have said simply, that clay is moistened earth–what sort of clay is not to the point. 
   • THEAETETUS: Theodorus was writing out for us something about roots, such as the roots of three or five, showing that they are incommensurable by the unit: he selected other examples up to seventeen –there he stopped. Now as there are innumerable roots, the notion occurred to us of attempting to include them all under one name or class. … SOCRATES: Come, you made a good beginning just now; let your own answer about roots be your model, and as you comprehended them all in one class, try and bring the many sorts of knowledge under one definition. 
2. Now he who knows perceives what he knows, and, as far as I can see at present, knowledge is perception. (the doctrine that whatever appears is to each one, that sense is knowledge, that to every individual and state what appears, is …) … 
   • Well, you have delivered yourself of a very important doctrine about knowledge; it is indeed the opinion of Protagoras, who has another way of expressing it. Man, he says, is the measure of all things, of the existence of things that are, and of the non-existence of things that are not: — … Does he not say that things are to you such as they appear to you, and to me such as they appear to me, and that you and I are men? 
   • A wise man is not likely to talk nonsense. Let us try to understand him: the same wind is blowing, and yet one of us may be cold and the other not, or one may be slightly and the other very cold? … Now is the wind, regarded not in relation to us but absolutely, cold or not; or are we to say, with Protagoras, that the wind is cold to him who is cold, and not to him who is not? … 
   • And ‘appears to him’ means the same as ‘he perceives.’ … Then perception is always of existence, and being the same as knowledge is unerring? 
   • I am about to speak of a high argument, in which all things are said to be relative; you cannot rightly call anything by any name, such as great or small, heavy or light, for the great will be small and the heavy light–there is no single thing or quality, but out of motion and change and admixture all things are becoming relatively to one another, which ‘becoming’ is by us incorrectly called being, but is really becoming, for nothing ever is, but all things are becoming. Summon all philosophers– Protagoras, Heracleitus, Empedocles, and the rest of them, one after another, and with the exception of Parmenides they will agree with you in this. Summon the great masters of either kind of poetry–Epicharmus, the prince of Comedy, and Homer of Tragedy; when the latter sings of ‘Ocean whence sprang the gods, and mother Tethys,’ does he not mean that all things are the offspring, of flux and motion? 
   • and there are plenty of other proofs which will show that motion is the source of what is called being and becoming, and inactivity of not-being and destruction; for fire and warmth, which are supposed to be the parent and guardian of all other things, are born of movement and of friction, which is a kind of motion; –is not this the origin of fire? 
   • And is not the bodily habit spoiled by rest and idleness, but preserved for a long time by motion and exercise? … And what of the mental habit? Is not the soul informed, and improved, and preserved by study and attention, which are motions; but when at rest, which in the soul only means want of attention and study, is uninformed, and speedily forgets whatever she has learned? … Then motion is a good, and rest an evil, to the soul as well as to the body?…  I may add, that breathless calm, stillness and the like waste and impair, while wind and storm preserve; and the palmary argument of all, which I strongly urge, is the golden chain in Homer, by which he means the sun, thereby indicating that so long as the sun and the heavens go round in their orbits, all things human and divine are and are preserved, but if they were chained up and their motions ceased, then all things would be destroyed, and, as the saying is, turned upside down. 
   • Then now apply his doctrine to perception, my good friend, and first of all to vision; that which you call white colour is not in your eyes, and is not a distinct thing which exists out of them. And you must not assign any place to it: for if it had position it would be, and be at rest, and there would be no process of becoming. 
   • Let us carry the principle which has just been affirmed, that nothing is self-existent, and then we shall see that white, black, and every other colour, arises out of the eye meeting the appropriate motion, and that what we call a colour is in each case neither the active nor the passive element, but something which passes between them, and is peculiar to each percipient; are you quite certain that the several colours appear to a dog or to any animal whatever as they appear to you? … Or that anything appears the same to you as to another man? Are you so profoundly convinced of this? Rather would it not be true that it never appears exactly the same to you, because you are never exactly the same? 
   • And if that with which I compare myself in size, or which I apprehend by touch, were great or white or hot, it could not become different by mere contact with another unless it actually changed; nor again, if the comparing or apprehending subject were great or white or hot, could this, when unchanged from within, become changed by any approximation or affection of any other thing.
   • The three axioms:
     • …. first, that nothing can become greater or less, either in number or magnitude, while remaining equal to itself—
     • …. Secondly, that without addition or subtraction there is no increase or diminution of anything, but only equality. 
     • …. Thirdly, that what was not before cannot be afterwards, without becoming and having become. 
   • I see, my dear Theaetetus, that Theodorus had a true insight into your nature when he said that you were a philosopher, for wonder is the feeling of a philosopher, and philosophy begins in wonder. He was not a bad genealogist who said that Iris (the messenger of heaven) is the child of Thaumas (wonder).
   • Far more ingenious are the brethren whose mysteries I am about to reveal to you. Their first principle is, that all is motion, and upon this all the affections of which we were just now speaking are supposed to depend: there is nothing but motion, which has two forms, one active and the other passive, both in endless number; and out of the union and friction of them there is generated a progeny endless in number, having two forms, sense and the object of sense, which are ever breaking forth and coming to the birth at the same moment. 
   • The purport is that all these things are in motion, as I was saying, and that this motion is of two kinds, a slower and a quicker; and the slower elements have their motions in the same place and with reference to things near them, and so they beget; but what is begotten is swifter, for it is carried to fro, and moves from place to place. 
   • for of the agent and patient, as existing in separation, no trustworthy conception, as they say, can be formed, for the agent has no existence until united with the patient, and the patient has no existence until united with the agent; and that which by uniting with something becomes an agent, by meeting with some other thing is converted into a patient.
   • And from all these considerations, as I said at first, there arises a general reflection, that there is no one self-existent thing, but everything is becoming and in relation; and being must be altogether abolished, although from habit and ignorance we are compelled even in this discussion to retain the use of the term. … in the language of nature all things are being created and destroyed, coming into being and passing into new forms; nor can any name fix or detain them; he who attempts to fix them is easily refuted. And this should be the way of speaking, not only of particulars but of aggregates; such aggregates as are expressed in the word ‘man,’ or ‘stone,’ or any name of an animal or of a class. 
   • Is it your opinion that nothing is but what becomes? –the good and the noble, as well as all the other things which we were just now mentioning? 
   • For you know that in all these cases the esse-percipi theory appears to be unmistakably refuted, since in dreams and illusions we certainly have false perceptions; and far from saying that everything is which appears, we should rather say that nothing is which appears.
   • But then, my boy, how can anyone contend that knowledge is perception, or that to every man what appears is? 
   • A question which I think that you must often have heard persons ask: — How can you determine whether at this moment we are sleeping, and all our thoughts are a dream; or whether we are awake, and talking to one another in the waking state? … You see, then, that a doubt about the reality of sense is easily raised, since there may even be a doubt whether we are awake or in a dream. And as our time is equally divided between sleeping and waking, in either sphere of existence the soul contends that the thoughts which are present to our minds at the time are true; and during one half of our lives we affirm the truth of the one, and, during the other half, of the other; and are equally confident of both. 
   • And may not the same be said of madness and other disorders? the difference is only that the times are not equal. … And is truth or falsehood to be determined by duration of time? 
   • Listen, then, to a statement of the other side of the argument, which is made by the champions of appearance. They would say, as I imagine–Can that which is wholly other than something, have the same quality as that from which it differs? and observe, Theaetetus, that the word ‘other’ means not ‘partially,’ but ‘wholly other.’ 
   • Let us take you and me, or anything as an example: –There is Socrates in health, and Socrates sick–Are they like or unlike?… THEAETETUS: I answer, they are unlike. And would you not say the same of Socrates sleeping and waking, or in any of the states which we were mentioning? … And I who am the patient, and that which is the agent, will produce something different in each of the two cases? … The wine which I drink when I am in health, appears sweet and pleasant to me? But when I am sick, the wine really acts upon another and a different person? … The combination of the draught of wine, and the Socrates who is sick, produces quite another result; which is the sensation of bitterness in the tongue, and the motion and creation of bitterness in and about the wine, which becomes not bitterness but something bitter; as I myself become not perception but percipient? … There is no other object of which I shall ever have the same perception, for another object would give another perception, and would make the percipient other and different; nor can that object which affects me, meeting another subject, produce the same, or become similar, for that too would produce another result from another subject, and become different…. Neither can I by myself, have this sensation, nor the object by itself, this quality. … When I perceive I must become percipient of something–there can be no such thing as perceiving and perceiving nothing; the object, whether it become sweet, bitter, or of any other quality, must have relation to a percipient; nothing can become sweet which is sweet to no one. … Then the inference is, that we (the agent and patient) are or become in relation to one another; there is a law which binds us one to the other, but not to any other existence, nor each of us to himself; and therefore we can only be bound to one another; so that whether a person says that a thing is or becomes, he must say that it is or becomes to or of or in relation to something else; but he must not say or allow anyone else to say that anything is or becomes absolutely:–such is our conclusion. … Then, if that which acts upon me has relation to me and to no other, I and no other am the percipient of it? … Then my perception is true to me, being inseparable from my own being; and, as Protagoras says, to myself I am judge of what is and what is not to me. … How then, if I never err, and if my mind never trips in the conception of being or becoming, can I fail of knowing that which I perceive? … Then you were quite right in affirming that knowledge is only perception; and the meaning turns out to be the same, whether with Homer and Heraclitus, and all that company, you say that all is motion and flux, or with the great sage Protagoras, that man is the measure of all things; or with Theaetetus, that, given these premises, perception is knowledge. Am I not right, Theaetetus, and is not this your new-born child, of which I have delivered you? What say you? 
   • SOCRATES: I am charmed with his (Protagoras) doctrine, that what appears is to each one, but I wonder that he did not begin his book on Truth with a declaration that a pig or a dog-faced baboon, or some other yet stranger monster which has sensation, is the measure of all things; then he might have shown a magnificent contempt for our opinion of him by informing us at the outset that while we were reverencing him like a God for his wisdom he was no better than a tadpole, not to speak of his fellow-men–would not this have produced an overpowering effect? For if truth is only sensation, and no man can discern another’s feelings better than he, or has any superior right to determine whether his opinion is true or false, but each, as we have several times repeated, is to himself the sole judge, and everything that he judges is true and right, why, my friend, should Protagoras be preferred to the place of wisdom and instruction, and deserve to be well paid, and we poor ignoramuses have to go to him, if each one is the measure of his own wisdom? Must he not be talking ‘ad captandum’ in all this? I say nothing of the ridiculous predicament in which my own midwifery and the whole art of dialectic is placed; for the attempt to supervise or refute the notions or opinions of others would be a tedious and enormous piece of folly, if to each man his own are right; and this must be the case if Protagoras’ Truth is the real truth, and the philosopher is not merely amusing himself by giving oracles out of the shrine of his book. 
   • Tell me, Theaetetus, in reference to what I was saying, are you not lost in wonder, like myself, when you find that all of a sudden you are raised to the level of the wisest of men, or indeed of the gods? –for you would assume the measure of Protagoras to apply to the gods as well as men? 
   • SOCRATES: And the way will be to ask whether perception is or is not the same as knowledge; for this was the real point of our argument, and with a view to this we raised (did we not?) those many strange questions. 
     • Shall we say that we know everything which we see and hear? for example, shall we say that not having learned, we do not hear the language of foreigners when they speak to us? or shall we say that we not only hear, but know what they are saying? Or again, if we see letters which we do not understand, shall we say that we do not see them? or shall we aver that, seeing them, we must know them? 
     • We shall say, Socrates, that we know what we actually see and hear of them–that is to say, we see and know the figure and colour of the letters, and we hear and know the elevation or depression of the sound of them; but we do not perceive by sight and hearing, or know, that which grammarians and interpreters teach about them. 
     • SOCRATES: Someone will say, Can a man who has ever known anything, and still has and preserves a memory of that which he knows, not know that which he remembers at the time when he remembers? I have, I fear, a tedious way of putting a simple question, which is only, whether a man who has learned, and remembers, can fail to know? 
     • Think: is not seeing perceiving, and is not sight perception?… As thus: he who sees knows, as we say, that which he sees; for perception and sight and knowledge are admitted to be the same. 
     • SOCRATES: But he who saw, and has knowledge of that which he saw, remembers, when he closes his eyes, that which he no longer sees. 
     • SOCRATES: Then the inference is, that a man may have attained the knowledge of something, which he may remember and yet not know, because he does not see; and this has been affirmed by us to be a monstrous supposition. 
     • Thus, then, the assertion that knowledge and perception are one, involves a manifest impossibility? 
     • SOCRATES: Then I will try to explain myself: just now we asked the question, whether a man who had learned and remembered could fail to know, and we showed that a person who had seen might remember when he had his eyes shut and could not see, and then he would at the same time remember and not know. But this was an impossibility. And so the Protagorean fable came to nought, and yours also, who maintained that knowledge is the same as perception. 
   • SOCRATES: Very good, Theodorus; you shall see how I will come to the rescue. If a person does not attend to the meaning of terms as they are commonly used in argument, he may be involved even in greater paradoxes than these. Shall I explain this matter to you or to Theaetetus? 
   • Then now let me ask the awful question, which is this: —Can a man know and also not know that which he knows? … When you are imprisoned in a well, as the saying is, and the self-assured adversary closes one of your eyes with his hand, and asks whether you can see his cloak with the eye which he has closed, how will you answer the inevitable man? … You have been proved to see that which you do not see; and you have already admitted that seeing is knowing, and that not-seeing is not-knowing… if an opponent had gone on to ask whether you can have a sharp and also a dull knowledge, and whether you can know near, but not at a distance, or know the same thing with more or less intensity, and so on without end. 
   • For do you really suppose that any one would admit the memory which a man has of an impression which has passed away to be the same with that which he experienced at the time? Assuredly not. …. Or, if he is afraid of making this admission, would he ever grant that one who has become unlike is the same as before he became unlike? Or would he admit that a man is one at all, and not rather many and infinite as the changes which take place in him? … But, O my good sir, he will say, come to the argument in a more generous spirit; and either show, if you can, that our sensations are not relative and individual, or, if you admit them to be so, prove that this does not involve the consequence that the appearance becomes, or, if you will have the word, is, to the individual only. As to your talk about pigs and baboons, you are yourself behaving like a pig, and you teach your hearers to make sport of my writings in the same ignorant manner; but this is not to your credit. For I declare that the truth is as I have written, and that each of us is a measure of existence and of non-existence. Yet one man may be a thousand times better than another in proportion as different things are and appear to him. And I am far from saying that wisdom and the wise man have no existence; but I say that the wise man is he who makes the evils which appear and are to a man, into goods which are and appear to him. And I would beg you not to press my words in the letter, but to take the meaning of them as I will explain them. Remember what has been already said, –that to the sick man his food appears to be and is bitter, and to the man in health the opposite of bitter. Now I cannot conceive that one of these men can be or ought to be made wiser than the other: nor can you assert that the sick man because he has one impression is foolish, and the healthy man because he has another is wise; but the one state requires to be changed into the other, the worse into the better. As in education, a change of state has to be effected, and the sophist accomplishes by words the change which the physician works by the aid of drugs. Not that anyone ever made another think truly, who previously thought falsely. For no one can think what is not, or, think anything different from that which he feels; and this is always true. But as the inferior habit of mind has thoughts of kindred nature, so I conceive that a good mind causes men to have good thoughts; and these which the inexperienced call true, I maintain to be only better, and not truer than others. And, O my dear Socrates, I do not call wise men tadpoles: far from it; I say that they are the physicians of the human body, and the husbandmen of plants–for the husbandmen also take away the evil and disordered sensations of plants, and infuse into them good and healthy sensations–aye and true ones; and the wise and good rhetoricians make the good instead of the evil to seem just to states; for whatever appears to a state to be just and fair, so long as it is regarded as such, is just and fair to it; but the teacher of wisdom causes the good to take the place of the evil, both in appearance and in reality. And in like manner the Sophist who is able to train his pupils in this spirit is a wise man, and deserves to be well paid by them. And so one man is wiser than another; and no one thinks falsely, and you, whether you will or not, must endure to be a measure. 
   • But I must beg you to put fair questions: for there is great inconsistency in saying that you have a zeal for virtue, and then always behaving unfairly in argument. The unfairness of which I complain is that you do not distinguish between mere disputation and dialectic: the disputer may trip up his opponent as often as he likes, and make fun; but the dialectician will be in earnest, and only correct his adversary when necessary, telling him the errors into which he has fallen through his own fault, or that of the company which he has previously kept. If you do so, your adversary will lay the blame of his own confusion and perplexity on himself, and not on you. He will follow and love you, and will hate himself, and escape from himself into philosophy, in order that he may become different from what he was. But the other mode of arguing, which is practised by the many, will have just the opposite effect upon him; and as he grows older, instead of turning philosopher, he will come to hate philosophy. I would recommend you, therefore, as I said before, not to encourage yourself in this polemical and controversial temper, but to find out, in a friendly and congenial spirit, what we really mean when we say that all things are in motion, and that to every individual and state what appears, is. 
   • Is knowledge and sensation the same or different?
   • At any rate, my good man (Theodorus), do not sheer off until we know whether you are a true measure of diagrams, or whether all men are equally measures and sufficient for themselves in astronomy and geometry, and the other branches of knowledge in which you are supposed to excel them. 
   • SOCRATES: There are many ways, Theodorus, in which the doctrine that every opinion of every man is true may be refuted; but there is more difficulty in proving that states of feeling, which are present to a man, and out of which arise sensations and opinions in accordance with them, are also untrue. And very likely I have been talking nonsense about them; for they may be unassailable, and those who say that there is clear evidence of them, and that they are matters of knowledge, may probably be right; in which case our friend Theaetetus was not so far from the mark when he identified perception and knowledge. 
   • The battle between “river-gods” and partisans of “the whole.” …. “that Oceanus and Tethys, the origin of all things…” and ‘Alone Being remains unmoved, which is the name for the all.‘ This is the language of Parmenides, Melissus, and their followers, who stoutly maintain that all being is one and self-contained, and has no place in which to move. 
   • Therefore I think that we had better begin by considering those whom we first accosted, ‘the river-gods,‘ and, if we find any truth in them, we will help them to pull us over, and try to get away from the others. But if the partisans of ‘the whole’ appear to speak more truly, we will fly off from the party which would move the immovable, to them. And if I find that neither of them have anything reasonable to say, we shall be in a ridiculous position, having so great a conceit of our own poor opinion and rejecting that of ancient and famous men. O Theodorus, do you think that there is any use in proceeding when the danger is so great? 
   • The nature of motion appears to be the question with which we begin. What do they mean when they say that all things are in motion? Is there only one kind of motion, or, as I rather incline to think, two?
     • tell me, then, when a thing changes from one place to another, or goes round in the same place, is not that what is called motion? 
     • But when a thing, remaining on the same spot, grows old, or becomes black from being white, or hard from being soft, or undergoes any other change, may not this be properly called motion of another kind? 
   • Say rather that it must be so. Of motion then there are these two kinds, ‘change,‘ and ‘motion in place.‘ 
   • And now, having made this distinction, let us address ourselves to those who say that all is motion, and ask them whether all things according to them have the two kinds of motion, and are changed as well as move in place, or is one thing moved in both ways, and another in one only? 
   • And if they are to be in motion, and nothing is to be devoid of motion, all things must always have every sort of motion? 
   • Consider a further point: did we not understand them to explain the generation of heat, whiteness, or anything else, in some such manner as the following: — were they not saying that each of them is moving between the agent and the patient, together with a perception, and that the patient ceases to be a perceiving power and becomes a percipient, and the agent a quale instead of a quality? … Then I will take concrete instances: I mean to say that the producing power or agent becomes neither heat nor whiteness but hot and white, and the like of other things. … For I must repeat what I said before, that neither the agent nor patient have any absolute existence, but when they come together and generate sensations and their objects, the one becomes a thing of a certain quality, and the other a percipient. … But now, since not even white continues to flow white, and whiteness itself is a flux or change which is passing into another colour, and is never to be caught standing still, can the name of any colour be rightly used at all? … How is that possible, Socrates, either in the case of this or of any other quality–if while we are using the word the object is escaping in the flux? … Then we must not speak of seeing any more than of not-seeing, nor of any other perception more than of any non-perception, if all things partake of every kind of motion? 
   • Here, then, is a fine result: we corrected our first answer in our eagerness to prove that nothing is at rest. But if nothing is at rest, every answer upon whatever subject is equally right: you may say that a thing is or is not thus; or, if you prefer, ‘becomes’ thus; and if we say ‘becomes,’ we shall not then hamper them with words expressive of rest. … Yes, Theodorus, except in saying ‘thus’ and ‘not thus.’ But you ought not to use the word ‘thus,’ for there is no motion in ‘thus’ or in ‘not thus.’ The maintainers of the doctrine have as yet no words in which to express themselves, and must get a new language. I know of no word that will suit them, except perhaps ‘no how,’ which is perfectly indefinite. 
   • And so, Theodorus, we have got rid of your friend without assenting to his doctrine, that every man is the measure of all things—a wise man only is a measure; neither can we allow that knowledge is perception, certainly not on the hypothesis of a perpetual flux, unless perchance our friend Theaetetus is able to convince us that it is.
   • And if any one were to ask you: With what does a man see black and white colours? and with what does he hear high and low sounds? –you would say, if I am not mistaken, ‘With the eyes and with the ears.’ … The free use of words and phrases, rather than minute precision, is generally characteristic of a liberal education, and the opposite is pedantic; but sometimes precision is necessary, and I believe that the answer which you have just given is open to the charge of incorrectness; for which is more correct, to say that we see or hear with the eyes and with the ears, or through the eyes and through the ears.
   • Yes, my boy, for no one can suppose that in each of us, as in a sort of Trojan horse, there are perched a number of unconnected senses, which do not all meet in some one nature, the mind, or whatever we please to call it, of which they are the instruments, and with which through them we perceive objects of sense. 
   • Very good; and now tell me what is the power which discerns, not only in sensible objects, but in all things, universal notions, such as those which are called being and not-being, and those others about which we were just asking–what organs will you assign for the perception of these notions? … THEAETETUS: You are thinking of being and not being, likeness and unlikeness, sameness and difference, and also of unity and other numbers which are applied to objects of sense; and you mean to ask, through what bodily organ the soul perceives odd and even numbers and other arithmetical conceptions. … Indeed, Socrates, I cannot answer; my only notion is, that these, unlike objects of sense, have no separate organ, but that the mind, by a power of her own, contemplates the universals in all things. 
   • You are a beauty, Theaetetus, and not ugly, as Theodorus was saying; for he who utters the beautiful is himself beautiful and good. And besides being beautiful, you have done me a kindness in releasing me from a very long discussion, if you are clear that the soul views some things by herself and others through the bodily organs. For that was my own opinion, and I wanted you to agree with me. … And to which class would you refer being or essence; for this, of all our notions, is the most universal? THEAETETUS: I should say, to that class which the soul aspires to know of herself. 
   • The simple sensations which reach the soul through the body are given at birth to men and animals by nature, but their reflections on the being and use of them are slowly and hardly gained, if they are ever gained, by education and long experience.
   • And can a man attain truth who fails of attaining being? 
   • And can he who misses the truth of anything, have a knowledge of that thing?
   • Then knowledge does not consist in impressions of sense, but in reasoning about them; in that only, and not in the mere impression, truth and being can be attained? 
   • Then perception, Theaetetus, can never be the same as knowledge or science? THEAETETUS: Clearly not, Socrates; and knowledge has now been most distinctly proved to be different from perception. 
   • But the original aim of our discussion was to find out rather what knowledge is than what it is not; at the same time we have made some progress, for we no longer seek for knowledge in perception at all, but in that other process, however called, in which the mind is alone and engaged with being. 
3. I cannot say, Socrates, that all opinion is knowledge, because there may be a false opinion; but I will venture to assert, that knowledge is true opinion:
   • Are there two sorts of opinion, one true and the other false; and do you define knowledge to be the true? 
   • How there can be false opinion–that difficulty still troubles the eye of my mind; and I am uncertain whether I shall leave the question, or begin over again in a new way. 
   • Well, and what is the difficulty? Do we not speak of false opinion, and say that one man holds a false and another a true opinion, as though there were some natural distinction between them? 
   • That point being now determined, must we not say that he who has an opinion, must have an opinion about something which he knows or does not know? 
   • But surely he cannot suppose what he knows to be what he does not know, or what he does not know to be what he knows? 
   • Where, then, is false opinion? For if all things are either known or unknown, there can be no opinion which is not comprehended under this alternative, and so false opinion is excluded. 
   • May we not suspect the simple truth to be that he who thinks about anything, that which is not, will necessarily think what is false, whatever in other respects may be the state of his mind? 
   • Is it possible for any man to think that which is not, either as a self-existent substance or as a predicate of something else? 
   • Then no one can think that which is not, either as a self- existent substance or as a predicate of something else? THEAETETUS: Clearly not. SOCRATES: Then to think falsely is different from thinking that which is not? 
   • Then false opinion has no existence in us, either in the sphere of being or of knowledge? 
   • May we not suppose that false opinion or thought is a sort of heterodoxy; a person may make an exchange in his mind, and say that one real object is another real object. For thus he always thinks that which is, but he puts one thing in place of another; and missing the aim of his thoughts, he may be truly said to have false opinion. THEAETETUS: Now you appear to me to have spoken the exact truth: when a man puts the base in the place of the noble, or the noble in the place of the base, then he has truly false opinion. … that false opinion is heterodoxy, or the thought of something else? 
   • And do you mean by conceiving, the same which I mean? THEAETETUS: What is that? SOCRATES: I mean the conversation which the soul holds with herself in considering of anything. I speak of what Iscarcely understand; but the soul when thinking appears to me to be just talking–asking questions of herself and answering them, affirming and denying. And when she has arrived at a decision, either gradually or by a sudden impulse, and has at last agreed, and does not doubt, this is called her opinion. I say, then, that to form an opinion is to speak, and opinion is a word spoken, –I mean, to oneself and in silence, not aloud or to another: 
   • Then when any one thinks of one thing as another, he is saying to himself that one thing is another? … But do you ever remember saying to yourself that the noble is certainly base, or the unjust just; or, best of all–have you ever attempted to convince yourself that one thing is another? Nay, not even in sleep, did you ever venture to say to yourself that odd is even, or anything of the kind? … And do you suppose that any other man, either in his senses or out of them, ever seriously tried to persuade himself that an ox is a horse, or that two are one? 
   • Then no one who has either both or only one of the two objects in his mind can think that the one is the other. And therefore, he who maintains that false opinion is heterodoxy is talking nonsense; for neither in this, any more than in the previous way, can false opinion exist in us. 
   • I think that we were wrong in denying that a man could think what he knew to be what he did not know; and that there is a way in which such a deception is possible.
   • Tell me, then, whether I am right in saying that you may learn a thing which at one time you did not know? 
   • The Wax tablet theory of the Mind
     • I would have you imagine, then, that there exists in the mind of man a block of wax, which is of different sizes in different men; harder, moister, and having more or less of purity in one than another, and in some of an intermediate quality. 
     • Let us say that this tablet is a gift of Memory, the mother of the Muses; and that when we wish to remember anything which we have seen, or heard, or thought in our own minds, we hold the wax to the perceptions and thoughts, and in that material receive the impression of them as from the seal of a ring; and that we remember and know what is imprinted as long as the image lasts; but when the image is effaced, or cannot be taken, then we forget and do not know. 
     • I should begin by making a list of the impossible cases which must be excluded. (1) No one can think one thing to be another when he does not perceive either of them, but has the memorial or seal of both of them in his mind; nor can any mistaking of one thing for another occur, when he only knows one, and does not know, and has no impression of the other; nor can he think that one thing which he does not know is another thing which he does not know, or that what he does not know is what he knows; nor (2) that one thing which he perceives is another thing which he perceives, or that something which he perceives is something which he does not perceive; or that something which he does not perceive is something else which he does not perceive; or that something which he does not perceive is something which he perceives; nor again (3) can he think that something which he knows and perceives, and of which he has the impression coinciding with sense, is something else which he knows and perceives, and of which he has the impression coinciding with sense;–this last case, if possible, is still more inconceivable than the others; nor (4) can he think that something which he knows and perceives, and of which he has the memorial coinciding with sense, is something else which he knows; nor so long as these agree, can he think that a thing which he knows and perceives is another thing which he perceives; or that a thing which he does not know and does not perceive, is the same as another thing which he does not know and does not perceive;–nor again, can he suppose that a thing which he does not know and does not perceive is the same as another thing which he does not know; or that a thing which he does not know and does not perceive is another thing which he does not perceive:– 
     • Socrates can recognize Theodorus and Theaetetus, but he sees neither of them, nor does he perceive them in any other way; he cannot then by any possibility imagine in his own mind that Theaetetus is Theodorus. 
     • I, knowing one of you and not knowing the other, and perceiving neither, can never think him whom I know to be him whom I do not know. 
     • In the third case, not knowing and not perceiving either of you, I cannot think that one of you whom I do not know is the other whom I do not know. 
     • The only possibility of erroneous opinion is, when knowing you and Theodorus, and having on the waxen block the impression of both of you given as by a seal, but seeing you imperfectly and at a distance, I try to assign the right impression of memory to the right visual impression, and to fit this into its own print: if I succeed, recognition will take place; but if I fail and transpose them, putting the foot into the wrong shoe– that is to say, putting the vision of either of you on to the wrong impression, or if my mind, like the sight in a mirror, which is transferred from right to left, err by reason of some similar affection, then ‘heterodoxy’ and false opinion ensues. 
     • Or again, when I know both of you, and perceive as well as know one of you, but not the other, and my knowledge of him does not accord with perception—
     • I meant to say, that when a person knows and perceives one of you, his knowledge coincides with his perception, he will never think him to be some other person, whom he knows and perceives, and the knowledge of whom coincides with his perception—
     • But there was an omission of the further case, in which, as we now say, false opinion may arise, when knowing both, and seeing, or having some other sensible perception of both, I fail in holding the seal over against the corresponding sensation; like a bad archer, I miss and fall wide of the mark–and this is called falsehood. 
     • When, therefore, perception is present to one of the seals or impressions but not to the other, and the mind fits the seal of the absent perception on the one which is present, in any case of this sort the mind is deceived; in a word, if our view is sound, there can be no error or deception about things which a man does not know and has never perceived, but only in things which are known and perceived; in these alone opinion turns and twists about, and becomes alternately true and false;–true when the seals and impressions of sense meet straight and opposite–false when they go awry and crooked. 
     • And the origin of truth and error is as follows:–When the wax in the soul of any one is deep and abundant, and smooth and perfectly tempered, then the impressions which pass through the senses and sink into the heart of the soul, as Homer says in a parable, meaning to indicate the likeness of the soul to wax (Kerh Kerhos); these, I say, being pure and clear, and having a sufficient depth of wax, are also lasting, and minds, such as these, easily learn and easily retain, and are not liable to confusion, but have true thoughts, for they have plenty of room, and having clear impressions of things, as we term them, quickly distribute them into their proper places on the block. And such men are called wise. Do you agree? 
     • But when the heart of any one is shaggy–a quality which the all-wise poet commends, or muddy and of impure wax, or very soft, or very hard, then there is a corresponding defect in the mind–the soft are good at learning, but apt to forget; and the hard are the reverse; the shaggy and rugged and gritty, or those who have an admixture of earth or dung in their composition, have the impressions indistinct, as also the hard, for there is no depth in them; and the soft too are indistinct, for their impressions are easily confused and effaced. Yet greater is the indistinctness when they are all jostled together in a little soul, which has no room. These are the natures which have false opinion; for when they see or hear or think of anything, they are slow in assigning the right objects to the right impressions–in their stupidity they confuse them, and are apt to see and hear and think amiss–and such men are said to be deceived in their knowledge of objects, and ignorant. 
     • O Socrates, have you indeed discovered that false opinion arises neither in the comparison of perceptions with one another nor yet in thought, but in union of thought and perception? … You mean to argue that the man whom we only think of and do not see, cannot be confused with the horse which we do not see or touch, but only think of and do not perceive? … Well, but do you think that no one ever put before his own mind five and seven,–I do not mean five or seven men or horses, but five or seven in the abstract, which, as we say, are recorded on the waxen block, and in which false opinion is held to be impossible; did no man ever ask himself how many these numbers make when added together, and answer that they are eleven, while another thinks that they are twelve, or would all agree in thinking and saying that they are twelve? … Then do we not come back to the old difficulty? For he who makes such a mistake does think one thing which he knows to be another thing which he knows; but this, as we said, was impossible, and afforded an irresistible proof of the non-existence of false opinion, because otherwise the same person would inevitably know and not know the same thing at the same time. … Then false opinion cannot be explained as a confusion of thought and sense, for in that case we could not have been mistaken about pure conceptions of thought; and thus we are obliged to say, either that false opinion does not exist, or that a man may not know that which he knows; — which alternative do you prefer? 
     •  Let us attempt to explain the verb ‘to know.’ … You seem not to be aware that the whole of our discussion from the very beginning has been a search after knowledge, of which we are assumed not to know the nature. … And is it not shameless when we do not know what knowledge is, to be explaining the verb ‘to know‘? The truth is, Theaetetus, that we have long been infected with logical impurity. Thousands of times have we repeated the words ‘we know,’ and ‘do not know,’ and ‘we have or have not science or knowledge,’ as if we could understand what we are saying to one another, so long as we remain ignorant about knowledge; and at this moment we are using the words ‘we understand,’ ‘we are ignorant,’ as though we could still employ them when deprived of knowledge or science. …. THEAETETUS: But if you avoid these expressions, Socrates, how will you ever argue at all?…. I could not, being the man I am. The case would be different if I were a true hero of dialectic: and O that such an one were present! for he would have told us to avoid the use of these terms; at the same time he would not have spared in you and me the faults which I have noted. But, seeing that we are no great wits, shall I venture to say what knowing is? … for I think that the attempt may be worth making. 
   • Birds in an aviary theory of mind
     • You have heard the common explanation of the verb ‘to know’? … They explain the word ‘to know’ as meaning ‘to have knowledge.’ … I should like to make a slight change, and say ‘to possess’ knowledge. … I should distinguish ‘having’ from ‘possessing’: for example, a man may buy and keep under his control a garment which he does not wear; and then we should say, not that he has, but that he possesses the garment. Well, may not a man ‘possess’ and yet not ‘have’ knowledge in the sense of which I am speaking? As you may suppose a man to have caught wild birds—doves or any other birds–and to be keeping them in an aviary which he has constructed at home; we might say of him in one sense, that he always has them because he possesses them, might we not? … 
     • And yet, in another sense, he has none of them; but they are in his power, and he has got them under his hand in an enclosure of his own, and can take and have them whenever he likes; –he can catch any which he likes, and let the bird go again, and he may do so as often as he pleases. 
     • Once more, then, as in what preceded we made a sort of waxen figment in the mind, so let us now suppose that in the mind of each man there is an aviary of all sorts of birds–some flocking together apart from the rest, others in small groups, others solitary, flying anywhere and everywhere. 
     • We may suppose that the birds are kinds of knowledge, and that when we were children, this receptacle was empty; whenever a man has gotten and detained in the enclosure a kind of knowledge, he may be said to have learned or discovered the thing which is the subject of the knowledge: and this is to know. … Attend to what follows: must not the perfect arithmetician know all numbers, for he has the science of all numbers in his mind? … And he can reckon abstract numbers in his head, or things about him which are numerable? …  And to reckon is simply to consider how much such and such a number amounts to? …  And so he appears to be searching into something which he knows, as if he did not know it, for we have already admitted that he knows all numbers; –you have heard these perplexing questions raised? 
     • May we not pursue the image of the doves, and say that the chase after knowledge is of two kinds? one kind is prior to possession and for the sake of possession, and the other for the sake of taking and holding in the hands that which is possessed already. And thus, when a man has learned and known something long ago, he may resume and get hold of the knowledge which he has long possessed, but has not at hand in his mind. 
     • Then shall we say that about names we care nothing?–any one may twist and turn the words ‘knowing’ and ‘learning’ in any way which he likes, but since we have determined that the possession of knowledge is not the having or using it, we do assert that a man cannot not possess that which he possesses; and, therefore, in no case can a man not know that which he knows, but he may get a false opinion about it; for he may have the knowledge, not of this particular thing, but of some other;–when the various numbers and forms of knowledge are flying about in the aviary, and wishing to capture a certain sort of knowledge out of the general store, he takes the wrong one by mistake, that is to say, when he thought eleven to be twelve, he got hold of the ring-dove which he had in his mind, when he wanted the pigeon. … But when he catches the one which he wants, then he is not deceived, and has an opinion of what is, and thus false and true opinion may exist, and the difficulties which were previously raised disappear. I dare say that you agree with me, do you not? 
     • And so we are rid of the difficulty of a man’s not knowing what he knows, for we are not driven to the inference that he does not possess what he possesses, whether he be or be not deceived. And yet I fear that a greater difficulty is looking in at the window. 
     • How can the exchange of one knowledge for another ever become false opinion?
     • In the first place, how can a man who has the knowledge of anything be ignorant of that which he knows, not by reason of ignorance, but by reason of his own knowledge? And, again, is it not an extreme absurdity that he should suppose another thing to be this, and this to be another thing;–that, having knowledge present with him in his mind, he should still know nothing and be ignorant of all things?–you might as well argue that ignorance may make a man know, and blindness make him see, as that knowledge can make him ignorant. 
     • THEAETETUS: Perhaps, Socrates, we may have been wrong in making only forms of knowledge our birds: whereas there ought to have been forms of ignorance as well, flying about together in the mind, and then he who sought to take one of them might sometimes catch a form of knowledge, and sometimes a form of ignorance; and thus he would have a false opinion from ignorance, but a true one from knowledge, about the same thing. 
     • The hero of dialectic will retort upon us:–‘O my excellent friends, he will say, laughing, if a man knows the form of ignorance and the form of knowledge, can he think that one of them which he knows is the other which he knows? or, if he knows neither of them, can he think that the one which he knows not is another which he knows not? or, if he knows one and not the other, can he think the one which he knows to be the one which he does not know? or the one which he does not know to be the one which he knows? or will you tell me that there are other forms of knowledge which distinguish the right and wrong birds, and which the owner keeps in some other aviaries or graven on waxen blocks according to your foolish images, and which he may be said to know while he possesses them, even though he have them not at hand in his mind? And thus, in a perpetual circle, you will be compelled to go round and round, and you will make no progress.’ What are we to say in reply, Theaetetus? 
     • Are not his reproaches just, and does not the argument truly show that we are wrong in seeking for false opinion until we know what knowledge is; that must be first ascertained; then, the nature of false opinion? 
   • THEAETETUS: Knowledge was said by us to be true opinion; and true opinion is surely unerring, and the results which follow from it are all noble and good. SOCRATES: He who led the way into the river, Theaetetus, said ‘The experiment will show;’ and perhaps if we go forward in the search, we may stumble upon the thing which we are looking for; but if we stay where we are, nothing will come to light. … The trail soon comes to an end, for a whole profession is against us. … The profession of the great wise ones who are called orators and lawyers; for these persuade men by their art and make them think whatever they like, but they do not teach them. Do you imagine that there are any teachers in the world so clever as to be able to convince others of the truth about acts of robbery or violence, of which they were not eye- witnesses, while a little water is flowing in the clepsydra? … And would you not say that persuading them is making them have an opinion? 
   • When, therefore, judges are justly persuaded about matters which you can know only by seeing them, and not in any other way, and when thus judging of them from report they attain a true opinion about them, they judge without knowledge, and yet are rightly persuaded, if they have judged well. 
   • And yet, O my friend, if true opinion in law courts and knowledge are the same, the perfect judge could not have judged rightly without knowledge; and therefore I must infer that they are not the same.
4. THEAETETUS: That is a distinction, Socrates, which I have heard made by someone else, but I had forgotten it. He said that true opinion, combined with reason, was knowledge, but that the opinion which had no reason was out of the sphere of knowledge; and that things of which there is no rational account are not knowable–such was the singular expression which he used–and that things which have a reason or explanation are knowable. (that true opinion, combined with definition or rational explanation, is knowledge…). 
   • Excellent; but then, how did he distinguish between things which are and are not ‘knowable’? I wish that you would repeat to me what he said, and then I shall know whether you and I have heard the same tale.
   • the primeval letters or elements out of which you and I and all other things are compounded, have no reason or explanation; you can only name them, but no predicate can be either affirmed or denied of them, for in the one case existence, in the other non-existence is already implied, neither of which must be added, if you mean to speak of this or that thing by itself alone. 
   • Thus, then, the elements or letters are only objects of perception, and cannot be defined or known; but the syllables or combinations of them are known and expressed, and are apprehended by true opinion. 
   • When, therefore, any one forms the true opinion of anything without rational explanation, you may say that his mind is truly exercised, but has no knowledge; for he who cannot give and receive a reason for a thing, has no knowledge of that thing; but when he adds rational explanation, then, he is perfected in knowledge and may be all that I have been denying of him. 
   • What might seem to be the most ingenious notion of all: —That the elements or letters are unknown, but the combination or syllables known. 
   • What was the way in which we learned letters? and, first of all, are we right in saying that syllables have a definition, but that letters have no definition? 
   • THEAETETUS: But how can anyone, Socrates, tell the elements of an element? I can only reply, that S is a consonant, a mere noise, as of the tongue hissing; B, and most other letters, again, are neither vowel-sounds nor noises. Thus letters may be most truly said to be undefined; for even the most distinct of them, which are the seven vowels, have a sound only, but no definition at all. 
   • Take the case of the two letters S and O, which form the first syllable of my own name; must not he who knows the syllable, know both of them? … He knows, that is, the S and O? … But can he be ignorant of either singly and yet know both together? … But if he cannot know both without knowing each, then if he is ever to know the syllable, he must know the letters first; and thus the fine theory has again taken wings and departed. 
   • Yes, we did not keep watch properly. Perhaps we ought to have maintained that a syllable is not the letters, but rather one single idea framed out of them, having a separate form distinct from them. … Let us assume then, as we now say, that the syllable is a simple form arising out of the several combinations of harmonious elements–of letters or of any other elements. … And it must have no parts. … Because that which has parts must be a whole of all the parts. Or would you say that a whole, although formed out of the parts, is a single notion different from all the parts? … And would you say that all and the whole are the same, or different? … Well, but is there any difference between all (in the plural) and the all (in the singular)? Take the case of number: –When we say one, two, three, four, five, six; or when we say twice three, or three times two, or four and two, or three and two and one, are we speaking of the same or of different numbers? … Of same (six). … Then as many things as have parts are made up of parts? …  But all the parts are admitted to be the all, if the entire number is the all? … Then the whole is not made up of parts, for it would be the all, if consisting of all the parts? … But is a part a part of anything but the whole? … And yet is not the all that of which nothing is wanting? … And is not a whole likewise that from which nothing is absent? but that from which anything is absent is neither a whole nor all; –if wanting in anything, both equally lose their entirety of nature. 
   • Then, as I was saying before, must not the alternative be that either the syllable is not the letters, and then the letters are not parts of the syllable, or that the syllable will be the same with the letters, and will therefore be equally known with them? … But if letters are not parts of syllables, can you tell me of any other parts of syllables, which are not letters? … No, indeed, Socrates; for if I admit the existence of parts in a syllable, it would be ridiculous in me to give up letters and seek for other parts. … Quite true, Theaetetus, and therefore, according to our present view, a syllable must surely be some indivisible form? … 
   • But do you remember, my friend, that only a little while ago we admitted and approved the statement, that of the first elements out of which all other things are compounded there could be no definition, because each of them when taken by itself is uncompounded; nor can one rightly attribute to them the words ‘being’ or ‘this,’ because they are alien and inappropriate words, and for this reason the letters or elements were indefinable and unknown? 
   • If, then, a syllable is a whole, and has many parts or letters, the letters as well as the syllable must be intelligible and expressible, since all the parts are acknowledged to be the same as the whole? 
   • We cannot, therefore, agree in the opinion of him who says that the syllable can be known and expressed, but not the letters. 
   • Why, that in learning you were kept trying to distinguish the separate letters both by the eye and by the ear, in order that, when you heard them spoken or saw them written, you might not be confused by their position. … And is the education of the harp-player complete unless he can tell what string answers to a particular note; the notes, as everyone would allow, are the elements or letters of music? 
   • Then, if we argue from the letters and syllables which we know to other simples and compounds, we shall say that the letters or simple elements as a class are much more certainly known than the syllables, and much more indispensable to a perfect knowledge of any subject; and if someone says that the syllable is known and the letter unknown, we shall consider that either intentionally or unintentionally he is talking nonsense? 
   • The meaning of the term “explanation.”
     • In the first place, the meaning may be, manifesting one’s thought by the voice with verbs and nouns, imaging an opinion in the stream which flows from the lips, as in a mirror or water. (the image or expression of the mind in speech;)
     • the second, which has just been mentioned, is a way of reaching the whole by an enumeration of the elements. 
     •  There is, further, the popular notion of telling the mark or sign of difference which distinguishes the thing in question from all others. 
   • And our opponent will probably laugh at us, just as he would if we professed to be grammarians and to give a grammatical account of the name of Theaetetus, and yet could only tell the syllables and not the letters of your name–that would be true opinion, and not knowledge; for knowledge, as has been already remarked, is not attained until, combined with true opinion, there is an enumeration of the elements out of which anything is composed. …. In the same general way, we might also have true opinion about a wagon; but he who can describe its essence by an enumeration of the hundred planks, adds rational explanation to true opinion, and instead of opinion has art and knowledge of the nature of a wagon, in that he attains to the whole through the elements. 
   • If you do, my friend; but I want to know first, whether you admit the resolution of all things into their elements to be a rational explanation of them, and the consideration of them in syllables or larger combinations of them to be irrational–is this your view? 
   • When a person at the time of learning writes the name of Theaetetus, and thinks that he ought to write and does write Th and e; but, again, meaning to write the name of Theododorus, thinks that he ought to write and does write T and e–can we suppose that he knows the first syllables of your two names? … And in that case, when he knows the order of the letters and can write them out correctly, he has right opinion? … 
   • But although we admit that he has right opinion, he will still be without knowledge? …  And yet he will have explanation, as well as right opinion, for he knew the order of the letters when he wrote; and this we admit to be explanation. … Then, my friend, there is such a thing as right opinion united with definition or explanation, which does not as yet attain to the exactness of knowledge.
   • But he, who having right opinion about anything, can find out the difference which distinguishes it from other things will know that of which before he had only an opinion. 
   • Suppose that I imagine Theaetetus to be a man who has nose, eyes, and mouth, and every other member complete; how would that enable me to distinguish Theaetetus from Theodorus, or from some outer barbarian? 
   • Or if I had further conceived of you, not only as having nose and eyes, but as having a snub nose and prominent eyes, should I have any more notion of you than of myself and others who resemble me? … Surely I can have no conception of Theaetetus until your snub- nosedness has left an impression on my mind different from the snub- nosedness of all others whom I have ever seen, and until your other peculiarities have a like distinctness; and so when I meet you to-morrow the right opinion will be re-called? … Then right opinion implies the perception of differences? 
   • And so, when the question is asked, What is knowledge? this fair argument will answer ‘Right opinion with knowledge,’–knowledge, that is, of difference, for this, as the said argument maintains, is adding the definition. 
   • But how utterly foolish, when we are asking what is knowledge, that the reply should only be, right opinion with knowledge of difference or of anything! And so, Theaetetus, knowledge is neither sensation nor true opinion, nor yet definition and explanation accompanying and added to true opinion? 
   • But if, Theaetetus, you should ever conceive afresh, you will be all the better for the present investigation, and if not, you will be soberer and humbler and gentler to other men, and will be too modest to fancy that you know what you do not know. These are the limits of my art; I can no further go, nor do I know aught of the things which great and famous men know or have known in this or former ages. The office of a midwife I, like my mother, have received from God; she delivered women, I deliver men; but they must be young and noble and fair.

• Theodorus attempt to defend/rehabilitate Protagoras’ orphan (the proposition that ‘What seems to a man, is to him.’) …  
  • SOCRATES: And are not we, Protagoras, uttering the opinion of man, or rather of all mankind, when we say that everyone thinks himself wiser than other men in some things, and their inferior in others? In the hour of danger, when they are in perils of war, or of the sea, or of sickness, do they not look up to their commanders as if they were gods, and expect salvation from them, only because they excel them in knowledge? Is not the world full of men in their several employments, who are looking for teachers and rulers of themselves and of the animals? and there are plenty who think that they are able to teach and able to rule. Now, in all this is implied that ignorance and wisdom exist among them, at least in their own opinion. … And wisdom is assumed by them to be true thought, and ignorance to be false opinion. … Shall we say that the opinions of men are always true, or sometimes true and sometimes false? In either case, the result is the same, and their opinions are not always true, but sometimes true and sometimes false. For tell me, Theodorus, do you suppose that you yourself, or any other follower of Protagoras, would contend that no one deems another ignorant or mistaken in his opinion? … But are there not thousands upon thousands who, whenever you form a judgment, take up arms against you and are of an opposite judgment and opinion, deeming that you judge falsely? 
  • And how about Protagoras himself? If neither he nor the multitude thought, as indeed they do not think, that man is the measure of all things, must it not follow that the truth of which Protagoras wrote would be true to no one? But if you suppose that he himself thought this, and that the multitude does not agree with him, you must begin by allowing that in whatever proportion the many are more than one, in that proportion his truth is more untrue than true. THEODORUS: That would follow if the truth is supposed to vary with individual opinion. …. And the best of the joke is, that he acknowledges the truth of their opinion who believe his own opinion to be false; for he admits that the opinions of all men are true. …  And does he not allow that his own opinion is false, if he admits that the opinion of those who think him false is true? 
  • Then all mankind, beginning with Protagoras, will contend, or rather, I should say that he will allow, when he concedes that his adversary has a true opinion–Protagoras, I say, will himself allow that neither a dog nor any ordinary man is the measure of anything which he has not learned–am I not right? 
  • And one thing which no one will deny is, that there are great differences in the understandings of men. 
  • … if however difference of opinion is to be allowed at all, surely we must allow it in respect of health or disease? for every woman, child, or living creature has not such a knowledge of what conduces to health as to enable them to cure themselves…. Or again, in politics, while affirming that just and unjust, honourable and disgraceful, holy and unholy, are in reality to each state such as the state thinks and makes lawful, and that in determining these matters no individual or state is wiser than another, still the followers of Protagoras will not deny that in determining what is or is not expedient for the community one state is wiser and one counsellor better than another–they will scarcely venture to maintain, that what a city enacts in the belief that it is expedient will always be really expedient. But in the other case, I mean when they speak of justice and injustice, piety and impiety, they are confident that in nature these have no existence or essence of their own–the truth is that which is agreed on at the time of the agreement, and as long as the agreement lasts; and this is the philosophy of many who do not altogether go along with Protagoras. … 
  • Had we not reached the point at which the partisans of the perpetual flux, who say that things are as they seem to each one, were confidently maintaining that the ordinances which the state commanded and thought just, were just to the state which imposed them, while they were in force; this was especially asserted of justice; but as to the good, no one had any longer the hardihood to contend of any ordinances which the state thought and enacted to be good that these, while they were in force, were really good;– 
  • Whatever be the term used, the good or expedient is the aim of legislation, and as far as she has an opinion, the state imposes all laws with a view to the greatest expediency; … That whole class has to do with the future, and laws are passed under the idea that they will be useful in after-time; which, in other words, is the future. 
  • Suppose now, that we ask Protagoras, or one of his disciples, a question:–O, Protagoras, we will say to him, Man is, as you declare, the measure of all things–white, heavy, light: of all such things he is the judge; for he has the criterion of them in himself, and when he thinks that things are such as he experiences them to be, he thinks what is and is true to himself. Is it not so? … And do you extend your doctrine, Protagoras (as we shall further say), to the future as well as to the present; and has he the criterion not only of what in his opinion is but of what will be, and do things always happen to him as he expected? For example, take the case of heat: —When an ordinary man thinks that he is going to have a fever, and that this kind of heat is coming on, and another person, who is a physician, thinks the contrary, whose opinion is likely to prove right? Or are they both right? –he will have a heat and fever in his own judgment, and not have a fever in the physician’s judgment? … And the vinegrower, if I am not mistaken, is a better judge of the sweetness or dryness of the vintage which is not yet gathered than the harp-player? … And in musical composition the musician will know better than the training master what the training master himself will hereafter think harmonious or the reverse? … And the cook will be a better judge than the guest, who is not a cook, of the pleasure to be derived from the dinner which is in preparation; for of present or past pleasure we are not as yet arguing; but can we say that everyone will be to himself the best judge of the pleasure which will seem to be and will be to him in the future?–nay, would not you, Protagoras, better guess which arguments in a court would convince any one of us than the ordinary man? …. To be sure, friend: who would have paid a large sum for the privilege of talking to him, if he had really persuaded his visitors that neither a prophet nor any other man was better able to judge what will be and seem to be in the future than everyone could for himself? … And legislation and expediency are all concerned with the future; and every one will admit that states, in passing laws, must often fail of their highest interests? 
  • Then we may fairly argue against your master (Protagoras), that he must admit one man to be wiser than another, and that the wiser is a measure: but I, who know nothing, am not at all obliged to accept the honour which the advocate of Protagoras was just now forcing upon me, whether I would or not, of being a measure of anything. 
  • THEODORUS: That is the best refutation of him, Socrates; although he is also caught when he ascribes truth to the opinions of others, who give the lie direct to his own opinion. 
  • Bear in mind the whole business of the midwives, and then you will see my meaning better: –No woman, as you are probably aware, who is still able to conceive and bear, attends other women, but only those who are past bearing. … The reason of this is said to be that Artemis–the goddess of childbirth–is not a mother, and she honours those who are like herself; but she could not allow the barren to be midwives, because human nature cannot know the mystery of an art without experience; and therefore she assigned this office to those who are too old to bear. … Did you ever remark that they are also most cunning matchmakers, and have a thorough knowledge of what unions are likely to produce a brave brood? … Then let me tell you that this is their greatest pride, more than cutting the umbilical cord. And if you reflect, you will see that the same art which cultivates and gathers in the fruits of the earth, will be most likely to know in what soils the several plants or seeds should be deposited. … and yet the true midwife is also the true and only matchmaker…. And like the midwives, I am barren, and the reproach which is often made against me, that I ask questions of others and have not the wit to answer them myself, is very just–the reason is, that the god compels me to be a midwife, but does not allow me to bring forth. … 
  • And if I abstract and expose your first-born, because I discover upon inspection that the conception which you have formed is a vain shadow, do not quarrel with me on that account, as the manner of women is when their first children are taken from them. For I have actually known some who were ready to bite me when I deprived them of a darling folly; they did not perceive that I acted from goodwill, not knowing that no god is the enemy of man–that was not within the range of their ideas; neither am I their enemy in all this, but it would be wrong for me to admit falsehood, or to stifle the truth. Once more, then, Theaetetus, I repeat my old question, ‘What is knowledge?’–and do not say that you cannot tell; but quit yourself like a man, and by the help of God you will be able to tell. 
  • Take a look round, then, and see that none of the uninitiated are listening. Now by the uninitiated I mean the people who believe in nothing but what they can grasp in their hands, and who will not allow that action or generation or anything invisible can have real existence. 

•  The picture of a lawyer:
  • … that those who have passed their days in the pursuit of philosophy are ridiculously at fault when they have to appear and speak in court. How natural is this!  
  • I mean to say, that those who have been trained in philosophy and liberal pursuits are as unlike those who from their youth upwards have been knocking about in the courts and such places, as a freeman is in breeding unlike a slave. … In the leisure spoken of by you, which a freeman can always command: he has his talk out in peace, and, like ourselves, he wanders at will from one subject to another, and from a second to a third,–if the fancy takes him, he begins again, as we are doing now, caring not whether his words are many or few; his only aim is to attain the truth. But the lawyer is always in a hurry; there is the water of the clepsydra driving him on, and not allowing him to expatiate at will: and there is his adversary standing over him, enforcing his rights; the indictment, which in their phraseology is termed the affidavit, is recited at the time: and from this he must not deviate. He is a servant, and is continually disputing about a fellow-servant before his master, who is seated, and has the cause in his hands; the trial is never about some indifferent matter, but always concerns himself; and often the race is for his life. 
  • The consequence has been, that he has become keen and shrewd; he has learned how to flatter his master in word and indulge him in deed; but his soul is small and unrighteous.
  • His condition, which has been that of a slave from his youth upwards, has deprived him of growth and uprightness and independence; dangers and fears, which were too much for his truth and honesty, came upon him in early years, when the tenderness of youth was unequal to them, and he has been driven into crooked ways; from the first he has practised deception and retaliation, and has become stunted and warped. And so he has passed out of youth into manhood, having no soundness in him; and is now, as he thinks, a master in wisdom. Such is the lawyer, Theodorus. 

• The picture of a philosopher:
  • In the first place, the lords of philosophy have never, from their youth upwards, known their way to the Agora, or the dicastery, or the council, or any other political assembly; they neither see nor hear the laws or decrees, as they are called, of the state written or recited; the eagerness of political societies in the attainment of offices–clubs, and banquets, and revels, and singing-maidens,–do not enter even into their dreams. 
  • Whether any event has turned out well or ill in the city, what disgrace may have descended to any one from his ancestors, male or female, are matters of which the philosopher no more knows than he can tell, as they say, how many pints are contained in the ocean. Neither is he conscious of his ignorance. 
  • For he does not hold aloof in order that he may gain a reputation; but the truth is, that the outer form of him only is in the city: his mind, disdaining the littlenesses and nothingnesses of human things, is ‘flying all abroad’ as Pindar says, measuring earth and heaven and the things which are under and on the earth and above the heaven, interrogating the whole nature of each and all in their entirety, but not condescending to anything which is within reach.
  • I will illustrate my meaning, Theodorus, by the jest which the clever witty Thracian handmaid is said to have made about Thales, when he fell into a well as he was looking up at the stars. She said, that he was so eager to know what was going on in heaven, that he could not see what was before his feet. This is a jest which is equally applicable to all philosophers. For the philosopher is wholly unacquainted with his next- door neighbour; he is ignorant, not only of what he is doing, but he hardly knows whether he is a man or an animal; he is searching into the essence of man, and busy in enquiring what belongs to such a nature to do or suffer different from any other; –I think that you understand me, Theodorus? 
  • And thus, my friend, on every occasion, private as well as public, as I said at first, when he appears in a law-court, or in any place in which he has to speak of things which are at his feet and before his eyes, he is the jest, not only of Thracian handmaids but of the general herd, tumbling into wells and every sort of disaster through his inexperience. His awkwardness is fearful, and gives the impression of imbecility. When he is reviled, he has nothing personal to say in answer to the civilities of his adversaries, for he knows no scandals of any one, and they do not interest him; and therefore he is laughed at for his sheepishness; and when others are being praised and glorified, in the simplicity of his heart he cannot help going into fits of laughter, so that he seems to be a downright idiot. When he hears a tyrant or king eulogized, he fancies that he is listening to the praises of some keeper of cattle–a swineherd, or shepherd, or perhaps a cowherd, who is congratulated on the quantity of milk which he squeezes from them; and he remarks that the creature whom they tend, and out of whom they squeeze the wealth, is of a less tractable and more insidious nature. Then, again, he observes that the great man is of necessity as ill-mannered and uneducated as any shepherd–for he has no leisure, and he is surrounded by a wall, which is his mountain-pen. Hearing of enormous landed proprietors of ten thousand acres and more, our philosopher deems this to be a trifle, because he has been accustomed to think of the whole earth; and when they sing the praises of family, and say that someone is a gentleman because he can show seven generations of wealthy ancestors, he thinks that their sentiments only betray a dull and narrow vision in those who utter them, and who are not educated enough to look at the whole, nor to consider that every man has had thousands and ten thousands of progenitors, and among them have been rich and poor, kings and slaves, Hellenes and barbarians, innumerable. And when people pride themselves on having a pedigree of twenty-five ancestors, which goes back to Heracles, the son of Amphitryon, he cannot understand their poverty of ideas. Why are they unable to calculate that Amphitryon had a twenty-fifth ancestor, who might have been anybody, and was such as fortune made him, and he had a fiftieth, and so on? He amuses himself with the notion that they cannot count, and thinks that a little arithmetic would have got rid of their senseless vanity. Now, in all these cases our philosopher is derided by the vulgar, partly because he is thought to despise them, and also because he is ignorant of what is before him, and always at a loss.
  • But, O my friend, when he draws the other into upper air, and gets him out of his pleas and rejoinders into the contemplation of justice and injustice in their own nature and in their difference from one another and from all other things; or from the commonplaces about the happiness of a king or of a rich man to the consideration of government, and of human happiness and misery in general–what they are, and how a man is to attain the one and avoid the other–when that narrow, keen, little legal mind is called to account about all this, he gives the philosopher his revenge; for dizzied by the height at which he is hanging, whence he looks down into space, which is a strange experience to him, he being dismayed, and lost, and stammering broken words, is laughed at, not by Thracian handmaidens or any other uneducated persons, for they have no eye for the situation, but by every man who has not been brought up a slave. Such are the two characters, Theodorus: the one of the freeman, who has been trained in liberty and leisure, whom you call the philosopher,–him we cannot blame because he appears simple and of no account when he has to perform some menial task, such as packing up bed-clothes, or flavouring a sauce or fawning speech; the other character is that of the man who is able to do all this kind of service smartly and neatly, but knows not how to wear his cloak like a gentleman; still less with the music of discourse can he hymn the true life aright which is lived by immortals or men blessed of heaven. 

Evils, Theodorus, can never pass away; for there must always remain something which is antagonistic to good. Having no place among the gods in heaven, of necessity they hover around the mortal nature, and this earthly sphere. Wherefore we ought to fly away from earth to heaven as quickly as we can; and to fly away is to become like God, as far as this is possible; and to become like him, is to become holy, just, and wise. But, O my friend, you cannot easily convince mankind that they should pursue virtue or avoid vice, not merely in order that a man may seem to be good, which is the reason given by the world, and in my judgment is only a repetition of an old wives’ fable. Whereas, the truth is that God is never in any way unrighteous–he is perfect righteousness; and he of us who is the most righteous is most like him. Herein is seen the true cleverness of a man, and also his nothingness and want of manhood. For to know this is true wisdom and virtue, and ignorance of this is manifest folly and vice. All other kinds of wisdom or cleverness, which seem only, such as the wisdom of politicians, or the wisdom of the arts, are coarse and vulgar. The unrighteous man, or the sayer and doer of unholy things, had far better not be encouraged in the illusion that his roguery is clever; for men glory in their shame–they fancy that they hear others saying of them, ‘These are not mere good-for-nothing persons, mere burdens of the earth, but such as men should be who mean to dwell safely in a state.’ Let us tell them that they are all the more truly what they do not think they are because they do not know it; for they do not know the penalty of injustice, which above all things they ought to know–not stripes and death, as they suppose, which evil-doers often escape, but a penalty which cannot be escaped. … There are two patterns eternally set before them; the one blessed and divine, the other godless and wretched: but they do not see them, or perceive that in their utter folly and infatuation they are growing like the one and unlike the other, by reason of their evil deeds; and the penalty is, that they lead a life answering to the pattern which they are growing like. And if we tell them, that unless they depart from their cunning, the place of innocence will not receive them after death; and that here on earth, they will live ever in the likeness of their own evil selves, and with evil friends–when they hear this they in their superior cunning will seem to be listening to the talk of idiots.

Better a little which is well done than a great deal imperfectly. 

… for to think truly is noble and to be deceived is base….