Lon Milo DuQuette is the author of Angels, Demons & Gods of the New Millenium and well-known student of the A. ·. A. ·., a school for magicians co-founded by Aleister Crowley. His explanation of the Tree of Life is given here in the public interest to show how the Qabalastic Tree of Life is taught and understood in that discipline.
DuQuette, L. M. (1997). Angels, Demons & Gods of the New Millenium. York Beach: Samuel Weiser, Inc.