In order to think fairly of morality, we must put two biological notions in its place: the taming of the wild beasts, and the rearing of a particular species.
The priests of all ages have always pretended that they wish to “improve.” … but we, of another persuasion would laugh if a lion-tamer ever wished to speak to us of his “improved” animals. As a rule, the taming of a beast is only achieved by deteriorating it: even the moral man is not a better man; he is rather a weaker man. But he is less harmful. — The Will to Power, Book II, A Criticism of Morality, 397.