¶ … Nicomachean Ethics, Aristotle's attempts to come to an understanding of human nature ultimately lead him to an understanding of justice. He attempts to understand how humans can reach true happiness, and delves deeply into the definitions of true happiness (eudaimonia) and virtue, and outlines how virtue and happiness are intertwined. Aristotle's Nicomachean Ethics deals with metaphysics, and focuses on ides like soul, happiness, virtue, and friendship. In Nicomachean Ethics, he concludes that happiness ultimately derives from activities of the soul that are in accordance with virtue. Says Aristotle "happiness is an activity of soul in accordance with perfect virtue" (Book I). Aristotle argues that the life that leads to the most happiness is a life of philosophical contemplation. However, he acknowledges that in order to achieve this life some members of a city-state must live a life of politics, adhering to the principles of justice, the highest of the virtues. Ultimately, Aristotle argues that a life devoted to virtues is second only in achieving eudaimonia to a life that is devoted to philosophical reflection.

In Book V of Nicomachean Ethics, Aristotle delves into a discussion of dikaiosune (justice). He notes that justice is extremely important in a society of free and equal people. Further, he makes a clear distinction between justice and ethics. Justice consists of following the rules, while ethics is comprised of doing the right and moral thing in cases where justice may lead to the wrong result.

To the philosopher Aristotle, justice is the ultimate virtue, as it requires having all other virtues, and unifies and orders the other virtues. The other virtues are friendliness, temperance, truthfulness, wit, courage, generosity, magnanimity, magnificence, right ambition, and good temper.

Says Aristotle of justice "all men mean by justice that kind of state of character which makes people disposed to do what is just and makes them act justly and wish for what is just; and similarly by injustice that state which makes them act unjustly and wish...

Natural justice is the same across time, and countries. From observation, Aristotle notes that this type of justice can be difficult to see. As such, different definitions of justice are held by different regimes and governments, in spite of their good intentions. Natural justice is unchanging in principle. In differentiating the two types of Justice, Aristotle notes, "Of political justice part is natural, part legal, natural, that which everywhere has the same force and does not exist by people's thinking this or that; legal, that which is originally indifferent, but when it has been laid down is not indifferent" (Book V).
According to Aristotle, legal justice is simply the law, and is often at odds with natural justice. In the city state legal and natural justice are necessarily intertwined in the laws of the city. Unlike natural justice which is unchanging in principle, legal justice can change often according to the time and needs of society. Noted Aristotle, "the things which are just not by nature but by human enactment are not everywhere the same, since constitutions also are not the same, though there is but one which is everywhere by nature the best" (Book V).

Interestingly, Aristotle refers to justice in the context of friendship. He notes, "when men are friends they have no need of justice, while when they are just they need friendship as well, and the truest form of justice is thought to be a friendly quality" (Book VII).

Aristotle felt that politics was the most authoritative science. It was politics that prescribed the sciences that were important for study within the city-state. For example, rhetoric and military science fall under the rubric of politics. Given that politics governs other sciences, all other sciences are ultimately directed toward achieving human good. Says Aristotle, "Even if the end is the same for an individual and for a city-state, that of the city-state seems at any rate greater and more complete to attain…