The real friend is another self.

The absolute good is not a matter of opinion but of nature.

Lay down this rule of friendship: neither ask nor consent to do what is wrong. The plea, 'for friendship's sake,' is a discreditable one, and should not be admitted for a moment. We should ask from friends and do for friends only what is good.

The whole of virtue consists in its practice.

Whatever that be which thinks, understands, wills, and acts, it is something celestial and divine.

Nothing is so great an adversary to those who make it their business to please as expectation.

Friendship was given by nature to be an assistant to virtue, not a companion in vice.