The vicious lover is the follower of earthly Love who desires the body rather than the soul; his heart is set on what is mutable and must therefore be inconstant. And as soon as the body he loves begins to pass the first flower of its beauty, he "spreads his wings and flies away," giving the lie to all his pretty speeches and dishonoring his vows, whereas the lover whose heart is touched by moral beauties is constant all his life, for he has become one with what will never fade.

183e, M. Joyce, trans, Collected Dialogues of Plato (1961), p. 537 - The Symposium