ION: Yes.
SOCRATES: You would argue, as I should, that when one art is of one kind of knowledge and another of another, they are different?
ION: Yes.
SOCRATES: Yes, surely; for if the subject of knowledge were the same, there would be no meaning in saying that the arts were different,—if they both gave the same knowledge. For example, I know that here are five fingers, and you know the same. And if I were to ask whether I and you became acquainted with this fact by the help of the same art of arithmetic, you would acknowledge that we did?
ION: Yes.
SOCRATES: Tell me, then, what I was intending to ask you,—whether this holds universally? Must the same art have the same subject of knowledge, and different arts other subjects of knowledge?
ION: That is my opinion, Socrates.
SOCRATES: Then he who has no knowledge of a particular art will have no right judgment of the sayings and doings of that art?
ION: Very true.
SOCRATES: Then which will be a better judge of the lines which you were reciting from Homer, you or the charioteer?