The founders of Western philosophy disagreed about the ethics of eating meat. Plato's "Republic" has Socrates describe the ideal state as vegetarian. Pythagoras believed that humans and animals were equal and therefore disapproved of meat consumption, as did Plutarch, whereas Zeno and Epicurus were vegetarian but allowed meat-eating in their philosophy. Conversely, Aristotle's "Politics" assert that animals, as inferior beings, exist to serve humans, including as food. Augustine drew on Aristotle to argue that the universe's natural hierarchy allows humans to eat animals, and animals to eat plants. Enlightenment philosophers were likewise divided. Descartes wrote that animals are merely animated machines, and Kant considered them inferior beings for lack of discernment; means rather than ends. But Voltaire and Rousseau disagreed. The latter argued that meat-eating is a social rather than a natural act, because children are not interested in meat.