Socrates SOC. The man who was leading the way through the river, ¹ 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; 201a but if we stay still, we shall discover nothing.

Theaetetus THEAET. You are right; let us go on with our investigation.

Socrates SOC. Well, then, this at least calls for slight investigation; for you have a whole profession which declares that true opinion is not knowledge.

Theaetetus THEAET. How so? What profession is it?

Socrates 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, ² 201b 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?

Theaetetus THEAET. I certainly do not think so; but I think they can persuade them.

Socrates SOC. And persuading them is making them have an opinion, is it not?

Theaetetus THEAET. Of course.

Socrates 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, 201c they have judged without knowledge, though they are rightly persuaded, if the judgement they have passed is correct, have they not?

Theaetetus THEAET. Certainly.

Socrates 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.

Theaetetus 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, 201d 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.

Socrates 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.

Theaetetus 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.

Socrates SOC. Listen then, while I relate it to you—“a dream for a dream.” I in turn 201e 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, 202a 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; 202b 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, 202c 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?

Theaetetus THEAET. That was it exactly.

Socrates SOC. Are you satisfied, then, and do you state it in this way, that true opinion accompanied by reason is knowledge?

Theaetetus THEAET. Precisely.

Socrates 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?

Theaetetus THEAET. I, at any rate, Socrates, think our present statement is good.

Socrates 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.

Theaetetus THEAET. What point?

Socrates SOC. Just that which seems to be the cleverest; the assertion that the elements are unknowable and the class of combinations 202e is knowable.

Theaetetus THEAET. Is that not right?

Socrates SOC. We are sure to find out, for we have as hostages the examples which he who said all this used in his argument.

Theaetetus THEAET. What examples?

Socrates SOC. The elements in writing, the letters of the alphabet, and their combinations, the syllables ³; or do you think the author of the statements we are discussing had something else in view?

Theaetetus THEAET. No; those are what he had in view.

Socrates SOC. Let us, then, take them up and examine them, or rather, let us examine ourselves and see whether it was in accordance with this theory, or not, that we learned letters. First then, the syllables have a rational explanation, but the letters have not?

Theaetetus THEAET. I suppose so.

Socrates SOC. I think so, too, decidedly. Now if anyone should ask about the first syllable of Socrates; “Theaetetus, tell me, what is SO?” What would you reply?

Theaetetus THEAET. I should say “S and O.”

Socrates SOC. This, then, is your explanation of the syllable?

Theaetetus THEAET. Yes.

Socrates SOC. Come now, in the same manner give me the explanation of the S.

Theaetetus THEAET. How can one give any elements of an element? For really, Socrates, the S is a voiceless letter, ⁴ a mere noise, as of the tongue hissing; B again has neither voice nor noise, nor have most of the other letters; and so it is quite right to say that they have no explanation, seeing that the most distinct of them, the seven vowels, have only voice, but no explanation whatsoever.

Socrates SOC. In this point, then, my friend, it would seem that we have reached a right conclusion about knowledge.

Theaetetus THEAET. I think we have.

Socrates SOC. But have we been right in laying down the principle that whereas the letter is unknowable, yet the syllable is knowable?

Theaetetus THEAET. Probably.

Socrates SOC. Well then, shall we say that the syllable is the two letters, or, if there be more than two, all of them, or is it a single concept that has arisen from their combination?

Theaetetus THEAET. I think we mean all the letters it contains.

Socrates SOC. Now take the case of two, S and O. The two together are the first syllable of my name. He who knows it knows the two letters, does he not?

Theaetetus THEAET. Of course.

Socrates SOC. He knows, that is, the S and the O.

Theaetetus THEAET. Yes.

Socrates SOC. How is that? He is ignorant of each, and knowing neither of them he knows them both?

Theaetetus THEAET. That is monstrous and absurd, Socrates.

Socrates SOC. And yet if a knowledge of each letter is necessary before one can know both, he who is ever to know a syllable must certainly know the letters first, and so our fine theory will have run away and vanished!

Theaetetus THEAET. And very suddenly, too.

Socrates SOC. Yes, for we are not watching it carefully. Perhaps we ought to have said that the syllable is not the letters, but a single concept that has arisen from them, having a single form of its own, different from the letters.

Theaetetus THEAET. Certainly; and perhaps that will be better than the other way.

Socrates SOC. Let us look into that; we must not give up in such unmanly fashion a great and impressive theory.

Theaetetus THEAET. No, we must not.

Socrates SOC. Let it be, then, as we say now, that the syllable or combination is a single form arising out of the several conjoined elements, and that it is the same in words and in all other things.

Theaetetus THEAET. Certainly.

Socrates SOC. Therefore there must be no parts of it.

Theaetetus THEAET. How so?

Socrates SOC. Because if there are parts of anything, the whole must inevitably be all the parts; or do you assert also that the whole that has arisen out of the parts is a single concept different from all the parts?

Theaetetus THEAET. Yes, I do.

Socrates SOC. Do you then say that all and the whole are the same, 204b or that each of the two is different from the other?

Theaetetus THEAET. I am not sure; but you tell me to answer boldly, so I take the risk and say that they are different.

Socrates SOC. Your boldness, Theaetetus, is right; but whether your answer is so remains to be seen.

Theaetetus THEAET. Yes, certainly, we must see about that.

Socrates SOC. The whole, then, according to our present view, would differ from all?

Theaetetus THEAET. Yes.

Socrates SOC. How about this? Is there any difference between all in the plural and all in the singular? For instance, if we say one, two, three, 204c four, five, six, or twice three, or three times two, or four and two, or three and two and one, are we in all these forms speaking of the same or of different numbers?

Theaetetus THEAET. Of the same.

Socrates SOC. That is, of six?

Theaetetus THEAET. Yes.

Socrates SOC. Then in each form of speech we have spoken of all the six?

Theaetetus THEAET. Yes.

Socrates SOC. And again do we not speak of one thing when we speak of them all?

Theaetetus THEAET. Assuredly.

Socrates SOC. That is, of six?

Theaetetus THEAET. Yes.

Socrates SOC. Then in all things that are made up of number, we apply the same term to all in the plural and all in the singular?

Theaetetus THEAET. Apparently.

Socrates SOC. Here is another way of approaching the matter. The number of the fathom and the fathom are the same, are they not?

Theaetetus THEAET. Yes.

Socrates SOC. And of the furlong likewise.

Theaetetus THEAET. Yes.

Socrates SOC. And the number of the army is the same as the army, and all such cases are alike? In each of them all the number is all the thing.

Theaetetus THEAET. Yes.

Socrates SOC. And is the number of each anything but 204e the parts of each?

Theaetetus THEAET. No.

Socrates SOC. Everything that has parts, accordingly, consists of parts, does it not?

Theaetetus THEAET. Evidently.

Socrates SOC. But we are agreed that the all must be all the parts if all the number is to be the all. ⁵

Theaetetus THEAET. Yes.

Socrates SOC. Then the whole does not consist of parts, for if it consisted of all the parts it would be the all.

Theaetetus THEAET. That seems to be true.

Socrates SOC. But is a part a part of anything in the world but the whole?

Theaetetus THEAET. Yes, of the all.