Socrates SOC. You are putting up a brave fight, Theaetetus. But is not the all precisely that of which nothing is wanting?

Theaetetus THEAET. Necessarily.

Socrates SOC. And is not just this same thing, from which nothing whatsoever is lacking, a whole? For that from which anything is lacking is neither a whole nor all, which have become identical simultaneously and for the same reason.

Theaetetus THEAET. I think now that there is no difference between all and whole.

Socrates SOC. We were saying, were we not, that if there are parts of anything, the whole and all of it will be all the parts?

Theaetetus THEAET. Certainly.

Socrates SOC. Once more, then, as I was trying to say just now, if the syllable is not the letters, does it not follow necessarily 205b that it contains the letters, not as parts of it, or else that being the same as the letters, it is equally knowable with them?

Theaetetus THEAET. It does.

Socrates SOC. And it was in order to avoid this that we assumed that it was different from them?

Theaetetus THEAET. Yes.

Socrates SOC. Well then, if the letters are not parts of the syllable, can you mention any other things which are parts of it, but are not the letters ¹ of it?

Theaetetus THEAET. Certainly not. For if I grant that there are parts of the syllable, it would be ridiculous to give up the letters and look for other things as parts.

Socrates SOC. Without question, then, Theaetetus, the syllable would be, according to our present view, some indivisible concept.

Theaetetus THEAET. I agree.

Socrates SOC. Do you remember, then, my friend, that we admitted a little while ago, on what we considered good grounds, that there can be no rational explanation of the primary elements of which other things are composed, because each of them, when taken by itself, is not composite, and we could not properly apply to such an element even the expression “be” or “this,” because these terms are different and alien, and for this reason it is irrational and unknowable?

Theaetetus THEAET. I remember.

Socrates SOC. And is not this the sole reason why it is single in form and indivisible? I can see no other.

Theaetetus THEAET. There is no other to be seen.

Socrates SOC. Then the syllable falls into the same class with the letter, if it has no parts and is a single form?

Theaetetus THEAET. Yes, unquestionably.

Socrates SOC. If, then, the syllable is a plurality of letters and is a whole of which the letters are parts, the syllables and the letters are equally knowable and expressible, if all the parts were found to be the same as the whole.

Theaetetus THEAET. Certainly.

Socrates SOC. But if one and indivisible, then syllable and likewise letter are equally irrational and unknowable; for the same cause will make them so.

Theaetetus THEAET. I cannot dispute it.

Socrates SOC. Then we must not accept the statement of any one who says that the syllable is knowable and expressible, but the letter is not.

Theaetetus THEAET. No, not if we are convinced by our argument.

Socrates SOC. But would you not rather accept the opposite belief, judging by your own experience when you were learning to read?

Theaetetus THEAET. What experience?

Socrates SOC. In learning, you were merely constantly trying to distinguish between the letters both by sight and by hearing, keeping each of them distinct from the rest, that you might not be disturbed by their sequence when they were spoken or written.

Theaetetus THEAET. That is very true.

Socrates SOC. And in the music school was not perfect attainment 206b the ability to follow each note and tell which string produced it; and everyone would agree that the notes are the elements of music?

Theaetetus THEAET. Yes, that is all true.

Socrates SOC. Then if we are to argue from the elements and combinations in which we ourselves have experience to other things in general, we shall say that the elements as a class admit of a much clearer knowledge than the compounds and of a knowledge that is much more important for the complete attainment of each branch of learning, and if anyone says that the compound is by its nature knowable and the element unknowable, we shall consider that he is, intentionally or unintentionally, joking.

Theaetetus THEAET. Certainly.

Socrates SOC. Still other proofs of this might be brought out, I think; but let us not on that account lose sight of the question before us, which is: What is meant by the doctrine that the most perfect knowledge arises from the addition of rational explanation to true opinion?

Theaetetus THEAET. No, we must not.

Socrates SOC. Now what are we intended to understand by “rational explanation”? I think it means one of three things.

Theaetetus THEAET. What are they?

Socrates SOC. The first would be making one’s own thought clear through speech by means of verbs and nouns, imaging the opinion in the stream that flows through the lips, as in a mirror or water. Do you not think the rational explanation is something of that sort?

Theaetetus THEAET. Yes, I do. At any rate, we say that he who does that speaks or explains.

Socrates SOC. Well, that is a thing that anyone can do sooner or later; he can show what he thinks about anything, unless he is deaf or dumb from the first; and so 206e all who have any right opinion will be found to have it with the addition of rational explanation, and there will henceforth be no possibility of right opinion apart from knowledge.

Theaetetus THEAET. True.

Socrates SOC. Let us not, therefore, carelessly accuse him of talking nonsense who gave the definition of knowledge which we are now considering; for perhaps that is not what he meant. He may have meant that each person if asked about anything must be able in reply 207a to give his questioner an account of it in terms of its elements.

Theaetetus THEAET. As for example, Socrates?

Socrates SOC. As, for example, Hesiod, speaking of a wagon, says, a hundred pieces of wood in a wagon. ² Now I could not name the pieces, nor, I fancy, could you; but if we were asked what a wagon is, we should be satisfied if we could say “wheels, axle, body, rims, yoke.”

Theaetetus THEAET. Certainly.

Socrates SOC. But he, perhaps, would think we were ridiculous, just as he would if, on being asked about your name, we should reply by telling the syllables, 207b holding a right opinion and expressing correctly what we have to say, but should think we were grammarians and as such both possessed and were expressing as grammarians would the rational explanation of the name Theaetetus. He would say that it is impossible for anyone to give a rational explanation of anything with knowledge, until he gives a complete enumeration of the elements, combined with true opinion. That, I believe, is what was said before.

Theaetetus THEAET. Yes, it was.

Socrates SOC. So, too, he would say that we have right opinion about a wagon, but that he who can give an account of its essential nature 207c in terms of those one hundred parts has by this addition added rational explanation to true opinion and has acquired technical knowledge of the essential nature of a wagon, in place of mere opinion, by describing the whole in terms of its elements.

Theaetetus THEAET. Do you agree to that, Socrates?

Socrates SOC. If you, my friend, agree to it and accept the view that orderly description in terms of its elements is a rational account of anything, but that description in terms of syllables or still larger units is irrational, 207d tell me so, that we may examine the question.

Theaetetus THEAET. Certainly I accept it.

Socrates SOC. Do you accept it in the belief that anyone has knowledge of anything when he thinks that the same element is a part sometimes of one thing and sometimes of another or when he is of opinion that the same thing has as a part of it sometimes one thing and sometimes another?

Theaetetus THEAET. Not at all, by Zeus.

Socrates SOC. Then do you forget that when you began to learn to read you and the others did just that?

Theaetetus THEAET. Do you mean when we thought that sometimes one letter 207e and sometimes another belonged to the same syllable, and when we put the same letter sometimes into the proper syllable and sometimes into another?

Socrates SOC. That is what I mean.

Theaetetus THEAET. By Zeus, I do not forget, nor do I think that those have knowledge who are in that condition.

Socrates SOC. Take an example: When at such a stage in his progress a person in writing “Theaetetus” thinks he ought to write, 208a and actually does write, TH and E, and again in trying to write “Theodorus” thinks he ought to write, and does write, T and E, shall we say that he knows the first syllable of your names?

Theaetetus THEAET. No, we just now agreed that a person in such a condition has not yet gained knowledge.

Socrates SOC. Then there is nothing to prevent the same person from being in that condition with respect to the second and third and fourth syllables?

Theaetetus THEAET. No, nothing.

Socrates SOC. Then, in that case, he has in mind the orderly description in terms of letters, and will write “Theaetetus” with right opinion, when he writes the letters in order?

Theaetetus THEAET. Evidently.

Socrates SOC. But he is still, as we say, without knowledge, though he has right opinion?

Theaetetus THEAET. Yes.

Socrates SOC. Yes, but with his opinion he has rational explanation; for he wrote with the method in terms of letters in his mind, and we agreed that that was rational explanation.

Theaetetus THEAET. True.

Socrates SOC. There is, then, my friend, a combination of right opinion with rational explanation, which cannot as yet properly be called knowledge?

Theaetetus THEAET. There is not much doubt about it.

Socrates SOC. So it seems that the perfectly true definition of knowledge, which we thought we had, was but a golden dream. Or shall we wait a bit before we condemn it? Perhaps the definition to be adopted is not this, 208c but the remaining one of the three possibilities one of which we said must be affirmed by anyone who asserts that knowledge is right opinion combined with rational explanation.

Theaetetus THEAET. I am glad you called that to mind. For there is still one left. The first was a kind of vocal image of the thought, the second the orderly approach to the whole through the elements, which we have just been discussing, and what is the third?

Socrates SOC. It is just the definition which most people would give, that knowledge is the ability to tell some characteristic by which the object in question differs from all others.

Theaetetus THEAET. As an example of the method, what explanation can you give me, and of what thing?

Socrates SOC. As an example, if you like, take the sun: I think it is enough for you to be told that it is the brightest of the heavenly bodies that revolve about the earth.

Theaetetus THEAET. Certainly.

Socrates SOC. Understand why I say this. It is because, as we were just saying, if you get hold of the distinguishing characteristic by which a given thing differs from the rest, you will, as some say, get hold of the definition or explanation of it; but so long as you cling to some common quality, your explanation will pertain to all those objects to which the common quality belongs.

Theaetetus THEAET. I understand; and it seems to me that it is quite right to call that kind a rational explanation or definition.

Socrates SOC. Then he who possesses right opinion about anything and adds thereto a comprehension of the difference which distinguishes it from other things will have acquired knowledge of that thing of which he previously had only opinion.

Theaetetus THEAET. That is what we affirm.

Socrates SOC. Theaetetus, now that I have come closer to our statement, I do not understand it at all. It is like coming close to a scene-painting. ³ While I stood off at a distance, I thought there was something in it.

Theaetetus THEAET. What do you mean?