Plato's Republic is often referred to as the cornerstone of all Western philosophy. It is in the form of a dialogue. The use of dialogue was a common device for framing philosophical arguments and Plato's use of the dialogue is considered a classic in structure and clarity. When reading The Republic is must be borne in mind that Plato was writing 2,500 years ago and that the views he expresses are very much of their time. The main protagonist is Socrates who is cast as the narrator. He is detained by the enquiring minds of Cephalus, Polemarchus (the text takes place at his home), Thrasymachus, Lysias, Euthydemus, Niceratus, Charmantides and Cleitophon. Socrates has arrived to atttend the festival and at first tries to dissuade his friends from detaining him any further. To the Ancient Greeks festivals were very important occasions and the very human quality that Plato's imparts to the character of Socrates as he tries to fend off his friend's questions is remarkably familiar to modern readers.

The book explores the notion of an ideal society that is created and disputed throughout the book. The purpose of imagining the society is in order to discover the true meaning of Justice. The book starts when Socrates encounters Polemarchus and is invited back to his home, there, Cephalus, Polemarchus' father, greets Socrates and talks about ageing. Cephalus eventually leaves and Polemarchus is left to take up the debate and the theme turns to that of Justice.

Thrasymachus then takes up the argument complaining of how Socrates is simply asking more questions rather than answering. After Thrasymachus' argument Glaucon provides another view of Justice where Socrates then sets about depicting his ideal city state. In this state the rulers or 'guardians' as they are known, receive a special education and attention. The book then continues on this theme until Socrates realizes that until philosophers are kings or vice-versa, society will always keep its problems.