No thinker has had a more profound influence on Western civilisation than Aristotle. In the Middle Ages many questions were settled by appeal to his authority alone, and his position was so pre-eminent that he was often referred to simply as ‘the philosopher’. His work represents a vast, encyclopaedic treatment of virtually every field of knowledge: logic, rhetoric, ethics, politics, metaphysics, poetry, biology, zoology, physics and psychology. The depth and clarity of his understanding are remarkable, and nowhere more so than in the Nicomachean Ethics and Politics.