Justice found, in the city and in the soul

The city is built. Three classes: the rulers (philosopher-kings, still to be defined), the auxiliaries who fight to defend it, and the producers — farmers, craftsmen, merchants — who feed and clothe everyone. Socrates argues that the four cardinal virtues of Greek thought can be located in this structure. Wisdom is in the small ruling class, who alone know what is good for the whole. Courage is in the auxiliaries, who hold true to their training under pressure. Moderation is the harmony between the classes — every group accepting its place.

Justice is the last to be defined and the most important. Socrates locates it not in any single class but in the relationship: each part of the city doing its own proper work, none overreaching the others. A producer who tries to govern, or a guardian who turns to making money, breaks the city. Each class kept to its own sphere is justice. It is a remarkably structural answer: justice is not a feeling, not a rule, but a kind of order.

Then Socrates turns inward. The soul, he proposes, has the same three parts as the city. Reason calculates; spirit (the energetic, courageous part) defends; appetite hungers and reaches for things. He proves the parts are distinct by noting that we can be in conflict with ourselves — wanting and not wanting the same thing — which would be impossible if the soul were one thing. Justice in a soul, he says, is the same shape as justice in a city: each part doing its proper work, none overreaching, all under the rule of reason. Injustice is internal civil war. The center of the Republic's argument is now standing.