SOCRATES: And yet surely, my dear friend Ion, in a discussion about
arithmetic, where many people are speaking, and one speaks better than the
rest, there is somebody who can judge which of them is the good speaker?

ION: Yes.

SOCRATES: And he who judges of the good will be the same as he who judges
of the bad speakers?

ION: The same.

SOCRATES: And he will be the arithmetician?

ION: Yes.

SOCRATES: Well, and in discussions about the wholesomeness of food, when
many persons are speaking, and one speaks better than the rest, will he who
recognizes the better speaker be a different person from him who recognizes
the worse, or the same?

ION: Clearly the same.

SOCRATES: And who is he, and what is his name?

ION: The physician.

SOCRATES: And speaking generally, in all discussions in which the subject
is the same and many men are speaking, will not he who knows the good know
the bad speaker also? For if he does not know the bad, neither will he