Aristotle (384–322 bce), whose father was physician to King Amyntas III of Macedon and who later would tutor Alexander, son of King Philip II, studied for twenty years at the Academy of Plato in Athens. He later organised a competing school in the Lyceum, teaching a philosophical curriculum in fundamental respects opposed to Plato. He originated formal logic as part of a systematic study of the nature of scientific knowledge, and argued for a clear demarcation between theoretical, productive and practical forms of knowledge. Among theoretical sciences he distinguished natural science and mathematics from an investigation of ‘being qua being’, the branch of philosophy we refer to as metaphysics. His metaphysics argues against the Platonic notion of the separation of form from natural objects, insisting that natural objects are unities of matter and form. He insisted that these are the proper objects of natural science, while mathematics cognitively isolates the mathematical properties of natural objects for investigation. His science of nature stands in opposition not only to the Platonic conception of a world modelled by God on a separate world of forms, but also in opposition to attempts to account for all natural objects and processes by referring them to some fundamental material principles. Rather he argues for a complex, teleologically ordered natural world, and his rich, groundbreaking studies of animals is the centrepiece of his natural science. Similarly, his ethics and politics are crafted in self-conscious opposition to Plato: ethics is a search, not for the Good itself, but for the human good, which he identifies as a life of virtue guided by practical reason and which he refers to as eudaimonia. But human good is only fully achievable within a properly organised community, and thus Aristotle’s politics is a study of the various forms of political organisation, with a view to identifying the best such organisation that is practically achievable.