Humor is the only test of gravity, and gravity of humor; for a subject which will not bear raillery is suspicious, and a jest which will not bear serious examination is false wit.
It is possible to fail in many ways . . . while to succeed is possible only in one way (for which reason also one is easy and the other difficult - to miss the mark easy, to hit it difficult).
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.
If, therefore, there is any one superior in virtue and in the power of performing the best actions, him we ought to follow and obey, but he must have the capacity for action as well as virtue.
It [Justice] is complete virtue in the fullest sense, because it is the active exercise of complete virtue; and it is complete because its possessor can exercise it in relation to another person, and not only by himself.