THEAETETUS: True.
SOCRATES: But that, Theaetetus, was not the point of my question: we wanted to know not the subjects, nor yet the number of the arts or sciences, for we were not going to count them, but we wanted to know the nature of knowledge in the abstract. Am I not right?
THEAETETUS: Perfectly right.
SOCRATES: Let me offer an illustration: Suppose that a person were to ask about some very trivial and obvious thing—for example, What is clay? and we were to reply, that there is a clay of potters, there is a clay of oven-makers, there is a clay of brick-makers; would not the answer be ridiculous?
THEAETETUS: Truly.
SOCRATES: In the first place, there would be an absurdity in assuming that he who asked the question would understand from our answer the nature of 'clay,' merely because we added 'of the image-makers,' or of any other workers. How can a man understand the name of anything, when he does not know the nature of it?
THEAETETUS: He cannot.
SOCRATES: Then he who does not know what science or knowledge is, has no knowledge of the art or science of making shoes?
THEAETETUS: None.
SOCRATES: Nor of any other science?