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 13th-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 book examines this 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.