Porphyry

He who abstains from anything animate ... will be much more careful not to injure those of his own species. For he who loves the genus will not hate any species of animals.

Porphyry was, like Pythagoras, an advocate of vegetarianism on spiritual and ethical grounds. These two philosophers are perhaps the most famous vegetarians of classical antiquity. He wrote the On Abstinence from Animal Food, advocating against the consumption of animals, and he is cited with approval in vegetarian literature up to the present day.