SOCRATES: Which is probably correct--for how can there be knowledge apart from definition and true opinion? And yet there is one point in what has been said which does not quite satisfy me.

THEAETETUS: What was it?

SOCRATES: What might seem to be the most ingenious notion of all:--That the elements or letters are unknown, but the combination or syllables known.

THEAETETUS: And was that wrong?

SOCRATES: We shall soon know; for we have as hostages the instances which the author of the argument himself used.

THEAETETUS: What hostages?

SOCRATES: The letters, which are the clements; and the syllables, which are the combinations;--he reasoned, did he not, from the letters of the alphabet?

THEAETETUS: Yes; he did.

SOCRATES: Let us take them and put them to the test, or rather, test ourselves:--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: I think so.

SOCRATES: I think so too; for, suppose that some one asks you to spell the first syllable of my name:--Theaetetus, he says, what is SO?

THEAETETUS: I should reply S and O.

SOCRATES: That is the definition which you would give of the syllable?

THEAETETUS: I should.

SOCRATES: I wish that you would give me a similar definition of the S.

THEAETETUS: But how can any one, 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.

SOCRATES: Then, I suppose, my friend, that we have been so far right in our idea about knowledge?

THEAETETUS: Yes; I think that we have.

SOCRATES: Well, but have we been right in maintaining that the syllables can be known, but not the letters?

THEAETETUS: I think so.

SOCRATES: And do we mean by a syllable two letters, or if there are more, all of them, or a single idea which arises out of the combination of them?

THEAETETUS: I should say that we mean all the letters.

SOCRATES: 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?

THEAETETUS: Certainly.

SOCRATES: He knows, that is, the S and O?

THEAETETUS: Yes.

SOCRATES: But can he be ignorant of either singly and yet know both together?

THEAETETUS: Such a supposition, Socrates, is monstrous and unmeaning.

SOCRATES: 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.

THEAETETUS: Yes, with wonderful celerity.

SOCRATES: 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.

THEAETETUS: Very true; and a more likely notion than the other.

SOCRATES: Take care; let us not be cowards and betray a great and imposing theory.

THEAETETUS: No, indeed.

SOCRATES: Let us a.s.sume 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.

THEAETETUS: Very good.

SOCRATES: And it must have no parts.

THEAETETUS: Why?

SOCRATES: 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?

THEAETETUS: I should.

SOCRATES: And would you say that all and the whole are the same, or different?

THEAETETUS: I am not certain; but, as you like me to answer at once, I shall hazard the reply, that they are different.

SOCRATES: I approve of your readiness, Theaetetus, but I must take time to think whether I equally approve of your answer.

THEAETETUS: Yes; the answer is the point.

SOCRATES: According to this new view, the whole is supposed to differ from all?

THEAETETUS: Yes.

SOCRATES: 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?

THEAETETUS: Of the same.

SOCRATES: That is of six?