 Questions about animal consciousness in the Western tradition have their roots in ancient discussions about the nature of human beings, as filtered through the “modern” philosophy of Descartes. It would be anachronistic to read ideas about consciousness from today back into the ancient literature. Nevertheless, because consciousness is sometimes thought to be a uniquely human mental phenomenon, it is important to understand the origins of the idea that humans are qualitatively (and “qualia-tatively”) different from animals.