Plato Greater Hippias 290b (Loeb)

   Socrates: This reply, my most excellent friend, he not only will certainly not accept, but he will even jeer at me grossly and will say: "You lunatic, do you think Pheidias is a bad craftsman?" And I shall say, "Not in the least."

   Hippias: And you will be right, Socrates.

   Socrates: Yes, to be sure. Consequently when I agree that Pheidias is a good craftsman, [290b] "Well, then," he will say, "do you imagine that Pheidias did not know this beautiful that you speak of?" "Why do you ask that?" I shall say. "Because," he will say, "he did not make the eyes of his Athena of gold, nor the rest of her face, nor her hands and feet, if, that is, they were sure to appear most beautiful provided only they were made of gold, but he made them of ivory; evidently he made this mistake through ignorance, not knowing that it is gold which makes everything beautiful to which it is added." When he says that, what reply shall we make to him, Hippias?

   [290c] Hippias: That is easy; for we shall say that Pheidias did right; for ivory, I think, is beautiful.

   Socrates: "Why, then," he will say, "did he not make the middle parts of the eyes also of ivory, but of stone, procuring stone as similar as possible to the ivory? Or is beautiful stone also beautiful?" Shall we say that it is, Hippias?

   Hippias: Surely we shall say so, that is, where it is appropriate.

   Socrates: "But ugly when not appropriate?" Shall I agree, or not?

   Hippias: Agree, that is, when it is not appropriate.