They should rule who are able to rule best.
Verbally there is very general agreement; for both the general run of men and people of superior refinement say that it is happiness, and identify living well and doing well with being happy; but with regard to what happiness is they differ, and the many do not give the same account as the wise.
A sign of this is what happens in our actions, for we delight in contemplating the most accurately made images of the very things that are painful for us to see, such as the forms of the most contemptible insects and of dead bodies.
The man who is isolated, who is unable to share in the benefits of political association, or has no need to share because he is already self-sufficient, is no part of the polis, and must therefore be either a beast or a god.
When people are friends, they have no need of justice, but when they are just, they do need friendship in addition; and in the realm of the just things, the most just seems to be what involves friendship.