The Republic is Plato's most famous work and one of the seminal texts of Western philosophy and politics. The characters in this Socratic dialogue - including Socrates himself - discuss whether the just or unjust man is happier. They are the philosopher-kings of imagined cities and they also discuss the nature of philosophy and the soul among other things. In the first book, two definitions of justice are proposed but deemed inadequate. Returning debts owed, and helping friends while harming enemies are common sense definitions of justice that, Socrates shows, are inadequate in exceptional situations, and thus lack the rigidity demanded of a definition. Yet he does not completely reject them for each expresses a common sense notion of justice which Socrates will incorporate into his discussion of the just regime in books II through V. At the end of Book I, Socrates agrees with Polemarchus that justice includes helping friends, but says the just man would never do harm to anybody. Thrasymachus believes that Socrates has done the men present an injustice by saying this and attacks his character and reputation in front of the group, partly because he suspects that Socrates himself does not even believe harming enemies is unjust.