In antiquity, the Platonic philosopher Plutarch had already launched a major indictment against meat-eaters. He believed that eating meat was a matter of culinary pleasure, not a necessity for survival: as omnivores, humans can nourish themselves as they see fit. In De esu carnium, Plutarch states: "We have no reason to kill in order to eat."

Problem XXX is a short text, attributed by Seneca, Plutarch, and Cicero, to Aristotle on the subject of melancholy.