Socrates describes stories for educating the city's guardians. They should include heroic stories, omitting any passages that might cause children to fear death or the afterlife, since guardians should fear slavery more than death. Lying and falsehood are forbidden, though rulers may lie if they need to. Moderation in sex, food and drink are required. Above all, gods and heroes should not be shown engaging in anything unflattering.
The stories should be simple narration, not imitative dramatic works in which the poet might present evil characters, since to imitate evil is to become evil. Dramatic style is forbidden since it puts dishonorable words and thoughts into the mouths of gods and heroes who should only be uttering noble, virtuous words. Because the future guardians must specialize, learning only those skills required for their occupation, literature that shows one person being many things, or changing, would confuse them.
The idea that imitative literature, or fiction and drama, is evil and full of falsehoods is a core concept in Platonic thought. In this section, he is still discussing only those stories about gods and heroes, not those about mortal men. The emphasis on specialization in occupation even applies to literature.
Children should only be exposed to the good and the pure, so that they will become good and pure by following positive models. Their teachers should love the good and pure nature of the boys. Sexual contact between the men and boys is forbidden. The future guardians train for war. Their diet is simple and moderate. Those suffering from an incurable disease should be allowed to die. The seriously mentally ill should be killed.
The assumption is that non-sexual love fosters a love of knowledge, since both are good. Socrates' medical advice emphasizes the ability of the patient to contribute to the good of the city—someone who can't contribute should be eliminated.
Just as a judge needs experience in life and the nature of evil, though he himself must be virtuous, the ruler must be a man of experience and virtue. The rulers must love the city's welfare above all else. The guardians must be carefully tested to determine those most suited to rule. The best must be separated from the rest as potential rulers and further educated. Only the best are to be called guardians, the rest are warriors or "auxiliaries."
The good of the city is more important than the individual's good. Socrates would argue that individuals are happy because they are doing what they are best suited to do, but they have no choice.
To avoid questions about those chosen to rule from the others in the city, Socrates invents a myth that says all people were born from the earth. Thus there are three sorts of people. Those with gold in their nature are suited to rule. Those with silver are warriors, and those with iron and bronze, farmers and craftsmen, "producers." Sometimes a child is born to parents of a different metal; such children will be raised with those like themselves. Those who are gold will become rulers. If the city is led by someone who is not gold, prophecy says it will be destroyed. Socrates says children will learn this myth as a truth.
Although there is no class system in terms of whose children are rulers, whose are warriors, and whose are producers, once a child is associated with a particular role, it is permanent. Notice too that while he insists on "truth" in terms of literature, Socrates creates a state that is founded on an artificial myth.
The guardians and warriors are responsible for the defense of the city. The guardians may not own anything beyond what is necessary. By law all they need is supplied by the city. They will dine in mess halls and are forbidden to touch gold or silver, since it is sacrilege to mix the pure gold of their soul with earthly metal.
Socrates' concern is that if rulers are allowed to own property they will eventually abuse their power, ruling and accumulating wealth for personal gain, not the good of the city.