The Festival and the First Question — The Republic

The Republic begins at a festival for Bendis in the Piraeus, where Socrates and Glaucon are persuaded to stay for conversation at the home of the aged Cephalus. Their host says age brings peace when passions cool, but admits wealth eases old age by keeping poverty from forcing injustice. When Socrates asks what justice means, Cephalus offers the conventional answer: tell the truth and pay what you owe.

Socrates tests that formula with the borrowed sword and a friend gone mad, and Polemarchus inherits the argument with Simonides' saying that justice means helping friends and harming enemies. Each version breaks under questioning: who counts as a true friend, when is returning harm just, and how is justice useful beyond guarding unused money? Thrasymachus interrupts impatiently and declares that justice is whatever serves the stronger party, that rulers write laws for their own advantage, and that the unjust person with real power lives better than the merely honest citizen.

Socrates answers with analogies to crafts: a doctor's art aims at the patient's health, not the doctor's profit, and justice likewise should serve those it governs. He traps Thrasymachus into admitting that true rulers seek the good of subjects, then argues that injustice divides and weakens while justice harmonizes like health in the soul. Book I ends without a finished definition; Socrates admits he still does not know what justice is, yet Thrasymachus has posed the challenge that will drive the rest of the dialogue: why choose justice if its rewards are uncertain?