Some men are just as sure of the truth of their opinions as are others of what they know.

A state is not a mere society, having a common place, established for the prevention of mutual crime and for the sake of exchange. Political society exists for the sake of noble actions, and not mere companionship.

In poverty and other misfortunes of life, true friends are a sure refuge.

To give away money is an easy matter and in any man's power. But to decide to whom to give it and how large and when, and for what purpose and how, is neither in every man's power nor an easy matter.

The purpose of the present study is not as it is in other inquiries, the attainment of knowledge, we are not conducting this inquiry in order to know what virtue is, but in order to become good, else there would be no advantage in studying it. For that reason, it becomes necessary to examine the problem of our actions and to ask how they are to be performed. For as we have said, the actions determine what kind of characteristics are developed.

It is clear, then, that wisdom is knowledge having to do with certain principles and causes. But now, since it is this knowledge that we are seeking, we must consider the following point: of what kind of principles and of what kind of causes is wisdom the knowledge?

Since we think we understand when we know the explanation, and there are four types of explanation (one, what it is to be a thing; one, that if certain things hold it is necessary that this does; another, what initiated the change; and fourth, the aim), all these are proved through the middle term.