For it is owing to their wonder that men both now begin and at first began to philosophize... They were pursuing science in order to know, and not for any utilitarian end.

The self-indulgent man craves for all pleasant things... and is led by his appetite to choose these at the cost of everything else.

Friendship is a thing most necessary to life, since without friends no one would choose to live, though possessed of all other advantages.

Learning is not child's play; we cannot learn without pain.

Thus it is thought that justice is equality; and so it is, but not for all persons, only for those that are equal. Inequality also is thought to be just; and so it is, but not for all, only for the unequal. We make bad mistakes if we neglect this for whom when we are deciding what is just. The reason is that we are making judgements about ourselves, and people are generally bad judges where their own interests are involved.

Happiness is a state of activity.

Now, the causes being four, it is the business of the student of nature to know about them all, and if he refers his problems back to all of them, he will assign the "why" in the way proper to his science-the matter, the form, the mover, that for the sake of which.