Why, does not Homer speak a good deal about arts, in a good many places? For instance, about chariot-driving: if I can recall the lines, I will quote them to you.

No, I will recite them, for I can remember.

Tell me then what Nestor says to his son Antilochus, advising him to be careful about the turning-post in the horse-race in honor of Patroclus.

Bend thyself in the polished car slightly to the left of them; i.e. one of the two white stones, set up at each end of the course, which had been mentioned six lines before. and call to the right-hand horse and goad him on, while your hand slackens his reins. And at the post let your left-hand horse swerve close, so that the nave of the well-wrought wheel may seem to come up to the edge of the stone, which yet avoid to touch.Hom. Il. 23.335 ff.

Enough. Now, Ion, will a doctor or a charioteer be the better judge whether Homer speaks correctly or not in these lines?

A charioteer, of course.

Because he has this art, or for some other reason?

No, because it is his art.

And to every art has been apportioned by God a power of knowing a particular business? For I take it that what we know by the art of piloting we cannot also know by that of medicine.

No, to be sure.

And what we know by medicine, we cannot by carpentry also?

No, indeed.

And this rule holds for all the arts, that what we know by one of them we cannot know by another? But before you answer that, just tell me this: do you agree that one art is of one sort, and another of another?

Yes.

Do you argue this as I do, and call one art different from another when one is a knowledge of one kind of thing, and another a knowledge of another kind?

Yes.

Since, I suppose, if it were a knowledge of the same things—how could we say that one was different from another, when both could give us the same knowledge? Just as I know that there are five of these fingers, and you equally know the same fact about them; and if I should ask you whether both you and I know this same fact by the same art of numeration, or by different arts, you would reply, I presume, that it was by the same?

Yes.