Aristotle
Some animals are cunning and evil-disposed, as the fox; others, as the dog, are fierce, friendly, and fawning. Some are gentle and easily tamed, as the elephant; some are susceptible of shame, and watchful, as the goose. Some are jealous and fond of ornament, as the peacock.
He who is unable to live in society, or who has no need because he is sufficient for himself, must be either a beast or a god.
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.
The moral virtues, then, are produced in us neither by nature nor against nature. Nature, indeed, prepares in us the ground for their reception, but their complete formation is the product of habit.