Most true.
And may we not say the same of all things?
What?
[D] That there are three arts which are concerned with all things: one which uses, another which makes, a third which imitates them?
Yes.
Goodness of things relative to use; hence the maker of them is instructed by the user. And the excellence or beauty or truth of every structure, animate or inanimate, and of every action of man, is relative to the use for which nature or the artist has intended them.
True.
Then the user of them must have the greatest experience of them, and he must indicate to the maker the good or bad qualities which develop themselves in use; for example, the flute-player will tell the flute-maker which of his flutes is satisfactory to the performer; he will tell him how he ought [E]to make them, and the other will attend to his instructions?
Of course.
The one knows and therefore speaks with authority about the goodness and badness of flutes, while the other, confiding in him, will do what he is told by him?