Magick Liber Aba Book 4 Author:Aleister Crowley Magick, Liber ABA, Book 4 is widely considered to be the magnum opus of 20th century occultist Aleister Crowley. It is a lengthy treatise on Magick, his system of Western occult practice, synthesized from many sources, including Eastern Yoga, Hermeticism, medieval grimoires. It consists of four parts: Mysticism, Magick (Elementary Theory), Magic... more »k in Theory and Practice, and ??????-the Law (The Equinox of The Gods). It also includes numerous appendices presenting many rituals and explicatory papers. Liber ABA refers to this work being a part of Crowley's system of "libers". In most systems where letters are given numerical value, ABA adds up to 4 (thus the name Book 4). Much of the book was dictated to several of Crowley's students, who would also ask questions to get clarification. The principal collaborators were Mary Desti, Leila Waddell, and Mary Butts, all of whom were given coauthorship credit.« less