Aleister Crowley (1875-1947), was an English occultist, ceremonial magician, poet, painter, novelist, and mountaineer. He was the most widely read author in 20th-century occultism. He single-handedly redefined magic as a field of inquiry and endeavor through his books and the order that he led-the A.A. and the O.T.O. He is the author several books including The Book of the Law, 777 & Other Qabalistic Writings, and The Book of Thoth.