Israel Regardie was one of the most influential figures in the western esoteric tradition. Born in the east end of London in 1907, he became Aleister Crowley's secretary in 1928. After breaking with Crowley he wrote prolifically, becoming influenced by Christian mysticism, alchemy and Jungian psychology. In the 1940s he became involved in psychiatry and attempted to reconcile magic and psychology. For those readers unable to work through Regardie's extensive writings, this study of his spiritual and intellectual development will clarify his ideas and show the integrity of his visions across a number of disciplines.