"The heaviest penalty for declining to rule is to be ruled by someone inferior to yourself."

Plato's best-known work, and one of the world's most influential works of philosophy and political theory, both intellectually and historically, The Republic is widely acknowledged as the cornerstone of Western philosophy.

Presented in the form of a dialogue between Socrates and his students and fellow citizens, The Republic is an inquiry into the notion of a perfect community and the ideal individuals within it. Questions are raised, such as: What is goodness? What is reality? What is knowledge? What is the philosopher's role in society?

To explore the latter, he invents a story where ordinary men are prisoners in a cave, observing only the shadows of things, while philosophers venture outside the cave and see things as they really are, and whose task it is to return to the cave and tell the truth about what they have seen. This metaphor demonstrates the conflict between the world of senses, the world of ideas, and the philosopher's role to mediate between the two. He considers the natures of existing regimes and then proposes a series of hypothetical cities in comparison, culminating in Kallipolis, a utopian city-state ruled by a class of philosopher-kings.

In search of an ideal civilization, Socrates leads Glaucon, Polemarchus, Thrasymachus, and others in debates about various subjects, including justice, truth, class, and art.

• They discuss the meaning of justice and whether the just man is happier than the unjust man.
• He addresses the purpose of education and the role of both women and men as "guardians" of the people.
• What is goodness? What is reality? What is knowledge? What is the purpose of education?
• They discuss getting older, love, the immortality of the soul, and the role of the philosopher and of poetry in society.