Entitled "The Republic", this book is represented by Plato as one of the main works in political thought. The book displays a model for the ideal state and the virtuous city that Plato dreamed of. Through a distinctive political philosophical dialogue, Plato reviews his vision of this ideal country and puts different personalities about the philosopher Socrates for discussion. The features of the virtuous city appear in this dialogue, where each individual belongs to a class and works in a specific specialty, and the three powers that make up society are balanced: rationality, anger and lust. Plato focuses on the definition of the just ruler, opposite the authoritarian ruler, and governments are divided into four main types. However, the search for absolute justice remains the biggest challenge facing the philosopher.