To help bring clarity to their discussions, Socrates proposes that in order to discover justice as a concept, they must apply it holistically as opposed to an individualistic, circumstantial criteria. In order to accomplish this, the group imagines what the ideal city would be like.
In this ideal place, there would be three classes of people (producers, auxiliaries, and guardians) which would told they have have a corresponding metal which makes up their soul. Bronze for the producers, silver for the auxiliaries, and gold for the guardians. Each class would be determined by individual merit in accordance with what tasks they best perform. For example, if a man is best at digging ditches he will dig ditches for the rest of his life. Additionally, the members of one class can only produce children with members of the same class.
The citizens of this city (a total of around 30,000 individuals) would all share wealth, food, and shelter communally. Several core virtues such as wisdom (through the guardians), courage (through the auxiliaries), and moderation (through all classes dwelling together peacefully) will be emphasized to help preserve justice. Socrates emphasizes that the goal is to make a city as good as possible so that the populace is as content as possible. The end-goal is not just to make one person as happy as possible.
As a pupil of Socrates, Plato's construction of this ideal city, named Kallipolis, was much more than hypothesizing about mortar and stone. For Plato, Kallipolis was meant to reflect two drastically different things on two totally different...