Plato, one of the most ingenious and powerful thinkers in Western philosophy, born around 425 B.C. Plato investigated a wide range of topics. Dominant among his ideas is an immense discourse called The Republic. The main focus of Plato is a perfect society. He outlines a utopian society, out of his disapproval for the tension of political life. Plato lived through the Peloponnesian War (431-404 BC), in which much of Greece was devastated. This created poverty and political confusion and corruption. Therefore, Plato created a sketch of a society in which the problems he thought were present would be eased. Essentially, The Republic deals with the question of justice and therefore with the questions "what is a just state?" and "who is a just individual?"
Plato defines justice as mental health (harmonious whole) where each part has a function. Just like the senses -- each sensory organ is excellent if it performs its function, as the eye sees, the ear hears. Therefore, people are happy if they perform the tasks assigned to them by nature. This is the fundamental notion for his creation of an ideal city. It seems that everyone has a specific role to follow depending upon their abilities, both physically and mentally. What this means is that only a certain type of people have the capacity to hold an office, just as only a certain type of people have the ability to be farmers.
Therefore, justice only exists in a city when a division of labor takes place amongst its residents. The ideal city classifies people into what they do best. Those who have an arête (an excellence) for artistry would be artisans, or moneymakers, and those with the most reason- the philosophers- to guide the city's actions and perform in the cities best interest. A third class, auxiliaries, would be in charge of carrying out what the philosophers, guardians of the city, decided. Although, this system is a hierarchy with the philosophers at the top, but they are the only ones who can find universal truths and apply it and teach it to those who cannot see it.
Plato also has three other virtues to help categorize those within the city and find justice in the city itself- wisdom, courage, and moderation, all ideals that would sustain the city and nurture it. Philosophers posses wisdom, auxiliaries courage, and all classes poses moderation. Wisdom is the whole knowledge, which describes the rulers of the city. The rulers should be the ones who incorporate philosophy and ruling together to rule the city wisely. Courage describes the guardians, whose job was to defend the city from invasion and take new lands for the city. The third virtue of the ideal city was moderation which is the concept of self-control and knowing ones role, also the concept of "one man, one job". The ideal city described in the work is picture perfect because it brings harmony among the different kind of people and the virtues that go hand in hand to bring justice about.