The Myth of Er closes the Republic, and it is doing philosophical work rather than reporting a revelation. Plato has spent ten books arguing that justice is worth choosing for itself; the myth is the closing argument, and it makes a claim the argument alone could not: that the choice extends past this life, and that you will make it yourself.
Er, a soldier killed in battle, lies unburied and undecayed for twelve days, revives on the funeral pyre, and describes what he saw as a witness forbidden to drink. Souls arrive at a meadow where judges sit between two openings in the earth and two in the sky. The just are sent up on the right with their judgments fastened on them in front; the unjust down on the left, with theirs behind. Each pays tenfold, over a thousand years, for what they did — reward or penalty in equal accounting. Then they return to the meadow and camp there, the ones from below dusty and weeping, the ones from above clean, and they exchange stories.
Then the extraordinary part. They travel to a place where a shaft of light binds the heavens, and there stands the spindle of Necessity, its whorls turning, a Siren on each singing one note of the harmony, and the three Fates — Lachesis, Clotho, Atropos — attending. A herald scatters lots for the order of choosing, then lays out the pattern-lives on the ground: tyrannies, animals, obscure lives, athletes, exiles. And the herald announces the sentence the whole dialogue has been building toward: the responsibility belongs to the chooser; God is blameless.
What Er sees next is the argument. The soul who draws first place rushes in and takes the greatest tyranny without examining it, and only afterward reads the fine print — that it includes eating his own children. He beats his breast and blames fortune, and he is one of those who came down from a thousand years in heaven, having been decent by habit rather than by philosophy, and therefore untrained in choosing. Odysseus, drawing last, searches a long time and finds the life of an ordinary private man that everyone else had passed over, and takes it gladly. Souls choose in the shape of what they were: swans become men, men become swans.
After choosing, each is fixed to their Fate, passes under the throne of Necessity, and crosses the plain of Forgetting to the river Ameles, where all must drink some and the unwise drink more. At midnight there is thunder, and they are carried up to birth like shooting stars. Er is not permitted to drink, which is why he can report it.
The framework matters far beyond its length. It fixed for Western thought the idea that the afterlife is a moral accounting with a return trip, that the soul selects its circumstances, and that forgetting is what makes birth possible — and it hands the responsibility, finally, to the one who chooses.
