This book explores the remarkable life and work of Pierre Duhem, the Catholic physicist, philosopher, and historian whose groundbreaking contributions to mechanics, thermodynamics, and the origins of modern science remain highly influential. Fr. Stanley Jaki presents a vivid portrait of Duhem’s deep Catholic faith alongside his scientific genius, offering twenty-seven translated selections from Duhem’s writings that reveal his seamless integration of science and belief. Both a biography and a treasury of Duhem’s thought, it highlights his enduring legacy as one of history’s greatest Catholic intellectuals.