Ring of Gyges

In Book II of the Republic, Glaucon challenges Socrates with a story: a shepherd, Gyges, finds a ring that makes him invisible and uses it to seize a kingdom. Glaucon asks whether anyone — just or unjust — would refrain from wrongdoing if they could act unseen and unpunished.

The thought experiment sharpens the question driving the whole dialogue: is justice good in itself, or only for its rewards and reputation? Socrates’ long reply — that justice is the health and harmony of the soul, choiceworthy for its own sake — is Plato’s answer to the ring.