Paul Adrien Maurice Dirac was undoubtedly one of the most brilliant and influential physicists of the twentieth century. Between 1925 and 1934, this Nobel Laureate revolutionized physics with his contributions to quantum theory. This book, the first full length biography of Dirac, offers a comprehensive account of his life and presents his physics in its historical context, including known areas such as cosmology and classical electron theory. The author examines Dirac's successes and failures, and pays particular attention to Dirac's opposition to modern quantum electrodynamics - an opposition based on aesthetic objections. This book, which draws extensively from unpublished sources, including Dirac's correspondence with Bohr, Heisenberg, Pauli, Schroedinger, Gamow, and other physicists, is a history of modern physics as seen through one scientist's career.