Aquinas (1224-74) lived at a time when the Christian West was opening up to a wealth of Greek and Islamic philosophical speculation. An embodiment of the thirteenth-century ideal of a unified interpretation of reality (in which philosophy and theology work together in harmony), Aquinas was remarkable for the way in which he used and developed this legacy of ancient thought an achievement which led his contemporaries to regard him as an advanced thinker. Father Copleston's lucid and stimulating book examines this extraordinary man whose influence is perhaps greater today than in his own lifetime and his thought, relating his ideas wherever possible to problems as they are discussed today.