A state is an association of similar persons whose aim is the best life possible. What is best is happiness, and to be happy is an active exercise of virtue and a complete employment of it.
There is also a doubt as to what is to be the supreme power in the state: - Is it the multitude? Or the wealthy? Or the good? Or the one best man? Or a tyrant?
Of actions some aim at what is necessary and useful, and some at what is honorable. And the preference given to one or the other class of actions must necessarily be like the preference given to one or other part of the soul and its actions over the other; there must be war for the sake of peace, business for the sake of leisure, things useful and necessary for the sake of things honorable.
If purpose, then, is inherent in art, so is it in Nature also. The best illustration is the case of a man being his own physician, for Nature is like that - agent and patient at once.
Nor need it cause surprise that things disagreeable to the good man should seem pleasant to some men; for mankind is liable to many corruptions and diseases, and the things in question are not really pleasant, but only pleasant to these particular persons, who are in a condition to think them so.
In seeking for justice men seek for the mean or neutral, for the law is the mean. Again, customary laws have more weight, and relate to more important matters, than written laws, and a man may be a safer ruler than the written law, but not safer than the customary law.
Between friends there is no need for justice, but people who are just still need the quality of friendship; and indeed friendliness is considered to be justice in the fullest sense.