SOC. But shall we say that he is going to read or count that which he does not know, when we have granted that he knows all letters and all numbers? THEAET. But that too is absurd. SOC. Shall we then say that words are nothing to us, if it amuses anyone to drag the expressions know and learn one way and another, but since we set up the distinction that it is one thing to possess knowledge and another thing to have it, we affirm that it is impossible not to possess what one possesses, so that it never happens that a man does not know that which he knows, but that it is possible to conceive a false opinion about it? 
 
For it is possible to have not the knowledge of this thing, but some other knowledge instead, when in hunting for some one kind of knowledge, as the various kinds fly about, he makes a mistake and catches one instead of another; so in one example he thought eleven was twelve, because he caught the knowledge of twelve, which was within him, instead of that of eleven, caught a ringdove, as it were, instead of a pigeon. THEAET. Yes, that is reasonable. SOC. But when he catches the knowledge he intends to catch, he is not deceived and has true opinion, and so true and false opinion exist and none of the things
 
which formerly annoyed us interferes? Perhaps you will agree to this; or what will you do? THEAET. I will agree. SOC. Yes, for we have got rid of our difficulty about men not knowing that which they know; for we no longer find ourselves not possessing that which we possess, whether we are deceived about anything or not. However, another more dreadful disaster seems to be coming in sight. THEAET. What disaster? SOC. If the interchange of kinds of knowledge should ever turn out to be false opinion. THEAET. How so? SOC. Is it not the height of absurdity, in the first place for one who has knowledge of something to be ignorant of this very thing, not through ignorance but through his knowledge; secondly, for him to be of opinion that this thing is something else and something else is this thing—for the soul, when knowledge has come to it, to know nothing and be ignorant of all things? For by this argument there is nothing to prevent ignorance from coming to us and making us know something and blindness from making us see, if knowledge is ever to make us ignorant. THEAET. Perhaps, Socrates, we were not right in making the birds represent kinds of knowledge only, but we ought to have imagined kinds of ignorance also flying about in the soul with the others; then the hunter would catch sometimes knowledge and sometimes ignorance of the same thing, and through the ignorance he would have false, but through the knowledge true opinion. SOC. It is not easy, Theaetetus, to refrain from praising you. However, examine your suggestion once more. Let it be as you say: 

 
the man who catches the ignorance will, you say, have false opinion. Is that it? THEAET. Yes. SOC. But surely he will not also think that he has false opinion. THEAET. Certainly not. SOC. No, but true opinion, and will have the attitude of knowing that about which he is deceived. THEAET. Of course. SOC. Hence he will fancy that he has caught, and has, knowledge, not ignorance. THEAET. Evidently. SOC. Then, after our long wanderings, we have come round again to our first difficulty. For the real reasoner
 
will laugh and say, Most excellent Sirs, does a man who knows both knowledge and ignorance think that one of them, which he knows, is another thing which he knows; or, knowing neither of them, is he of opinion that one, which he does not know, is another thing which he does not know; or, knowing one and not the other, does he think that the one he does not know is the one he knows; or that the one he knows is the one he does not know? Or will you go on and tell me that there are kinds of knowledge of the kinds of knowledge and of ignorance, and that he who possesses these kinds of knowledge and has enclosed them in some sort of other ridiculous aviaries
 
or waxen figments, knows them, so long as he possesses them, even if he has them not at hand in his soul? And in this fashion are you going to be compelled to trot about endlessly in the same circle without making any progress? What shall we reply to this, Theaetetus? THEAET. By Zeus, Socrates, I don’t know what to say. SOC. Then, my boy, is the argument right in rebuking us and in pointing out that we were wrong to abandon knowledge and seek first for false opinion? 
 
It is impossible to know the latter until we have adequately comprehended the nature of knowledge. THEAET. As the case now stands, Socrates, we cannot help thinking as you say. SOC. To begin, then, at the beginning once more, what shall we say knowledge is? For surely we are not going to give it up yet, are we? THEAET. Not by any means, unless, that is, you give it up. SOC. Tell us, then, what definition will make us contradict ourselves least. THEAET. The one we tried before, Socrates; at any rate, I have nothing else to offer. SOC. What one? THEAET. That knowledge is true opinion; for true opinion is surely free from error and all its results are fine and good. SOC. The man who was leading the way through the river, A man who was leading the way through a river was asked if the water was deep. He replied αὐτὸ δείξει , the event itself will show (i.e. you can find out by trying). The expression became proverbial. Theaetetus, said: The result itself will show; and so in this matter, if we go on with our search, perhaps the thing will turn up in our path and of itself reveal the object of our search; 

 
but if we stay still, we shall discover nothing. THEAET. You are right; let us go on with our investigation. SOC. Well, then, this at least calls for slight investigation; for you have a whole profession which declares that true opinion is not knowledge. THEAET. How so? What profession is it? SOC. The profession of those who are greatest in wisdom, who are called orators and lawyers; for they persuade men by the art which they possess, not teaching them, but making them have whatever opinion they like. Or do you think there are any teachers so clever as to be able, in the short time allowed by the water-clock, The length of speeches in the Athenian law courts was limited by a water-clock. 
 
satisfactorily to teach the judges the truth about what happened to people who have been robbed of their money or have suffered other acts of violence, when there were no eyewitnesses? THEAET. I certainly do not think so; but I think they can persuade them. SOC. And persuading them is making them have an opinion, is it not? THEAET. Of course. SOC. Then when judges are justly persuaded about matters which one can know only by having seen them and in no other way, in such a case, judging of them from hearsay, having acquired a true opinion of them,
 
they have judged without knowledge, though they are rightly persuaded, if the judgement they have passed is correct, have they not? THEAET. Certainly. SOC. But, my friend, if true opinion and knowledge were the same thing in law courts, the best of judges could never have true opinion without knowledge; in fact, however, it appears that the two are different. THEAET. Oh yes, I remember now, Socrates, having heard someone make the distinction, but I had forgotten it. He said that knowledge was true opinion accompanied by reason,
 
but that unreasoning true opinion was outside of the sphere of knowledge; and matters of which there is not a rational explanation are unknowable—yes, that is what he called them—and those of which there is are knowable. SOC. I am glad you mentioned that. But tell us how he distinguished between the knowable and the unknowable, that we may see whether the accounts that you and I have heard agree. THEAET. But I do not know whether I can think it out; but if someone else were to make the statement of it, I think I could follow. SOC. Listen then, while I relate it to you— a dream for a dream. I in turn
 
	used to imagine that I heard certain persons say that the primary elements of which we and all else are composed admit of no rational explanation; SO. for each alone by itself can only be named, and no qualification can be added, neither that it is nor that it is not,

 
for that would at once be adding to it existence or non-existence, whereas we must add nothing to it, if we are to speak of that itself alone. Indeed, not even itself or that or each or alone or this or anything else of the sort, of which there are many, must be added; for these are prevalent terms which are added to all things indiscriminately and are different from the things to which they are added; but if it were possible to explain an element, and it admitted of a rational explanation of its own, it would have to be explained apart from everything else. But in fact none of the primal elements can be expressed by reason; 
 
they can only be named, for they have only a name; but the things composed of these are themselves complex, and so their names are complex and form a rational explanation; for the combination of names is the essence of reasoning. Thus the elements are not objects of reason or of knowledge, but only of perception, whereas the combinations of them are objects of knowledge and expression and true opinion. When therefore a man acquires without reasoning the true opinion about anything,
 
his mind has the truth about it, but has no knowledge; for he who cannot give and receive a rational explanation of a thing is without knowledge of it; but when he has acquired also a rational explanation he may possibly have become all that I have said and may now be perfect in knowledge. Is that the version of the dream you have heard, or is it different? THEAET. That was it exactly. SOC. Are you satisfied, then, and do you state it in this way, that true opinion accompanied by reason is knowledge? THEAET. Precisely. SOC. Can it be, Theaetetus, that we now, in this casual manner, have found out on this day what many wise men have long been seeking and have grown grey in the search? THEAET. I, at any rate, Socrates, think our present statement is good. SOC. Probably this particular statement is so; for what knowledge could there still be apart from reason and right opinion? One point, however, in what has been said is unsatisfactory to me. THEAET. What point? SOC. Just that which seems to be the cleverest; the assertion that the elements are unknowable and the class of combinations
 
is knowable. THEAET. Is that not right? SOC. We are sure to find out, for we have as hostages the examples which he who said all this used in his argument. THEAET. What examples? SOC. The elements in writing, the letters of the alphabet, and their combinations, the syllables Στοιχεῖον and συλλαβή originally general terms for element and combination, became the common words for letter and syllable. ; or do you think the author of the statements we are discussing had something else in view? THEAET. No; those are what he had in view.