The Symposium
"A bad man is the lover of the common type, who loves the body rather than the mind. He is not constant, because he loves something that is not constant: as soon as the bloom of the body fades, which is what attracted him, "he flies away and is gone", bringing disgrace on all he said and promised. But the man who loves goodness of character is constant throughout his life, since he has become united with something constant."

/Plato's dialogue with Apollodorus/