SOCRATES: As, for example, when Hesiod says that a waggon is made up of a hundred planks. Now, neither you nor I could describe all of them individually; but if any one asked what is a waggon, we should be content to answer, that a waggon consists of wheels, axle, body, rims, yoke.
THEAETETUS: Certainly.
SOCRATES: 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.
THEAETETUS: Yes.
SOCRATES: In the same general way, we might also have true opinion about a waggon; 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 waggon, in that he attains to the whole through the elements.
THEAETETUS: And do you not agree in that view, Socrates?
SOCRATES: 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?
THEAETETUS: Precisely.
SOCRATES: Well, and do you conceive that a man has knowledge of any element who at one time affirms and at another time denies that element of something, or thinks that the same thing is composed of different elements at different times?
THEAETETUS: Assuredly not.