The guardians are divided into rulers and subjects, or “auxiliaries.” Who goes into which category is to be determined by age, talent, and commitment to the good of the community. They should be tested by being confronted by various objects of fear and pleasure. They ought also to be tested to see how easily they can be deceived.

Socrates suggests that all groups must be subject to a “noble lie” (118). This says that everyone in the community was forged out of the earth, then sent above ground. As a result of this lie people feel that the community is their mother and their fellow citizens brothers and sisters. Part of this lie is that God made different people with different admixtures of metals: gold when making the rulers, silver when making the auxiliaries, and iron or copper when forming the farmers or other workers. This story teaches people to accept their roles in society. Furthermore, while in general parents give birth to children of similar metals, sometimes a child will be born that is of a different metal to its parents. When this happens, it should be brought up as part of a different part of the community.