SOCRATES: Will he have enough of knowledge if he is acquainted only with the divine circle and sphere, and knows nothing of our human spheres and circles, but uses only divine circles and measures in the building of a house?
PROTARCHUS: The knowledge which is only superhuman, Socrates, is ridiculous in man.
SOCRATES: What do you mean? Do you mean that you are to throw into the cup and mingle the impure and uncertain art which uses the false measure and the false circle?
PROTARCHUS: Yes, we must, if any of us is ever to find his way home.
SOCRATES: And am I to include music, which, as I was saying just now, is full of guesswork and imitation, and is wanting in purity?
PROTARCHUS: Yes, I think that you must, if human life is to be a life at all.
SOCRATES: Well, then, suppose that I give way, and, like a doorkeeper who is pushed and overborne by the mob, I open the door wide, and let knowledge of every sort stream in, and the pure mingle with the impure?
PROTARCHUS: I do not know, Socrates, that any great harm would come of having them all, if only you have the first sort.
SOCRATES: Well, then, shall I let them all flow into what Homer poetically terms 'a meeting of the waters'?
PROTARCHUS: By all means.