Therefore the good man ought to be a lover of self, since he will then both benefit himself by acting nobly and aid his fellows; but the bad man ought not to be a lover of self, since he will follow his base passions, and so injure both himself and his neighbors. With the bad man therefore, what he does is not in accord with what he ought to do, but the good man does what he ought, since intelligence always chooses for itself that which is best, and the good man obeys his intelligence.

The hardest victory is the victory over self.

Obstinate people can be divided into the opinionated, the ignorant, and the boorish.

Happiness is essentially perfect; so that the happy man requires in addition the goods of the body, external goods and the gifts of fortune, in order that his activity may not be impeded through lack of them.

Character is determined by choice, not opinion.

It is clear, then, that the earth must be at the centre and immovable, not only for the reasons already given, but also because heavy bodies forcibly thrown quite straight upward return to the point from which they started, even if they are thrown to an infinite distance. From these considerations then it is clear that the earth does not move and does not lie elsewhere than at the centre.

It is evident that the state is a creation of nature, and that man is by nature a political animal.