As in other natural compounds the conditions of a composite whole are not necessarily organic parts of it, so in a state or in any other combination forming a unity not everything is a part, which is a necessary condition. The members of an association have necessarily some one thing the same and common to all, in which they share equally or unequally for example, food or land or any other thing. But where there are two things of which one is a means and the other an end, they have nothing in common except that the one receives what the other produces. Such, for example, is the relation which workmen and tools stand to their work; the house and the builder have nothing in common, but the art of the builder is for the sake of the house. And so states require property, but property, even though living beings are included in it, is no part of a state; for a state is not a community of living beings only, but a community of equals, aiming at the best life possible. Now, whereas happiness is the highest good, being a realization and perfect practice of virtue, which some can attain, while others have little or none of it, the various qualities of men are clearly the reason why there are various kinds of states and many forms of government; for different men seek after happiness in different ways and by different means, and so make for themselves different modes of life and forms of government. We must see also how many things are indispensable to the existence of a state, for what we call the parts of a state will be found among the indispensables. Let us then enumerate the functions of a state, and we shall easily elicit what we want:
First, there must be food; secondly, arts, for life requires many instruments; thirdly, there must be arms, for the members of a community have need of them, and in their own hands, too, in order to maintain authority both against disobedient subjects and against external assailants; fourthly, there must be a certain amount of revenue, both for internal needs, and for the purposes of war; fifthly, or rather first, there must be a care of religion which is commonly called worship; sixthly, and most necessary of all there must be a power of deciding what is for the public interest, and what is just in men's dealings with one another.
These are the services which every state may be said to need. For a state is not a mere aggregate of persons, but a union of them sufficing for the purposes of life; and if any of these things be wanting, it is as we maintain impossible that the community can be absolutely self-sufficing. A state then should be framed with a view to the fulfillment of these functions. There must be husbandmen to procure food, and artisans, and a warlike and a wealthy class, and priests, and judges to decide what is necessary and expedient.