Socrates: "Since the beautiful is opposite of the ugly, they are two."
Glaucon: "Of course."
"And since they are two, each is one?"
"I grant that also."
"And the same account is true of the just and unjust, the good and the bad, and all the forms. Each of them is itself one, but because they manifest themselves everywhere in association with actions, bodies, and one another, each of them appears to be many."
"So, I draw this distinction: On one side are those you just now called lovers of sights, lovers of crafts, and practical people; on the other side are those we are now arguing about and whom one would alone call philosophers."
"How do you mean?"
"The lovers of sights and sounds like beautiful sounds, colors, shapes, and everything fashioned out of them, but their thought is unable to see and embrace the nature of the beautiful itself."
"That's for sure."
"In fact, there are very few people who would be able to reach the beautiful itself and see it by itself. Isn't that so?"
"What about someone who believes in beautiful things, but doesn't believe in the beautiful itself and isn't able to follow anyone who could lead him to the knowledge of it? Don't you think he is living in a dream rather than a wakened state? Isn't this dreaming: whether asleep or awake, to think that a likeness is not a likeness but rather the thing itself that it is like?"
"I certainly think that someone who does that is dreaming."
"But someone who, to take the opposite case, believes in the beautiful itself, can see both it and the things that participate in it and doesn't believe that the participants are it or that it itself is the participants--is he living in a dream or is he awake?"
"He's very much awake."
Republic Bk. V, 475e-476d, translation G.M.A Grube