The Republic by Plato Part 4 Page 27

But where, amid all this, is justice? son of Ariston, tell me where. Now that our city has been made habitable, light a candle and search, and get your brother and Polemarchus and the rest of our friends to help, and let us see where in it we can discover justice and where injustice, and in what they differ from one another, and which of them the man who would be happy should have for his portion, whether seen or unseen by gods and men.

Nonsense, said Glaucon: did you not promise to search yourself, saying that for you not to help justice in her need would be an impiety?

I do not deny that I said so, and as you remind me, I will be as good as my word; but you must join.

We will, he replied.

Well, then, I hope to make