To call the taming of an animal its “improvement” sounds almost like a joke to our ears. Whoever knows what is going on in menageries doubts that the beasts are “improved” there. They are weakened, they are made less harmful, and through the depressive effect of fear; through pain, through wounds, and through hunger they become sickly beasts… Physiologically speaking; in the struggle with beasts, to make them sick may be the only means of making them weak. This is the Church understood: it ruined man, it weakened him – but it claimed to have “improved” him.
Nietzsche, From The Twilight of the Idols.