Plato's assault on mimesis occurs in a couple of different sections of the Republic. Initially the most popular explanation is found in books II and III. Book I develops the discussion, along with Book II, where Plato's controversial argument begins. Its fundamental concept is the individual's need to live well. In contrast to Thrasymachus' perspective, Plato believes that the good life is not a selfish, moral appreciation of sensual capabilities and satisfactions, but a modest lifestyle based on reason and justice. To support Plato's perspective and demonstrate that justice is fundamental to a good life, he will have to state exactly what justice is, yet Socrates consistently disavows possessing expertise in such areas. What Socrates is able to do is obtain the relevant knowledge through a dialectical exploration in which his companions perform an essential function. As long as Socrates correctly asks the relevant questions to his companions, they may later have the ability to clearly explain what exactly justice is. He addresses this question in Book II, and then in due course presents the question of art. The development from justice to art unfolds as follows: Socrates states that justice persists in a city in addition to the individual soul, however it is easier to distinguish the characteristics of justice in a city, because it is easier to observe. Socrates therefore depends on the concept of social justice; once this is understood, the concept of individual justice can be easily discovered. Social justice is not just a matter of convention; it will originate in the nature of everything. A significant concept for the nature of justice is the fundamental reason why a city exists. Individuals form cities, as no individual is self-sufficient. To exist an individual must have food, clothing, shelter and protection from humans