For good is simple, evil manifold.

What is the essence of life? To serve others and to do good.

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.

To know what virtue is is not enough; we must endeavor to possess and to practice it, or in some other manner actually ourselves to become good.

Equality is of two kinds, numerical and proportional; by the first I mean sameness of equality in number or size; by the second, equality of ratios.

It is the characteristic of the magnanimous man to ask no favor but to be ready to do kindness to others.

Music has the power of producing a certain effect on the moral character of the soul, and if it has the power to do this, it is clear that the young must be directed to music and must be educated in it.