Crowley originally intended the Thoth deck to be a six-month project aimed at updating the traditional pictorial symbolism of the tarot. However, due to increased scope the project eventually spanned five years, between 1938 and 1943 and both artists died before publication in 1969 by Ordo Templi Orientis.
The illustrations of the deck feature symbolism based upon Crowley's incorporation of imagery from many disparate disciplines, including science and philosophy and various occult systems (as described in detail in his Book of Thoth).
Wasserman, James. Instructions for Aleister Crowley's Thoth Tarot Deck, included in the U.S. Games Systems publication of the deck.
Aleister Crowley (June 1974). The Book of Thoth: A Short Essay on the Tarot of the Egyptians, Being the Equinox Volume III No. V. Illustrated by Frieda Harris. Samuel Weiser, Inc. p. 308. ISBN978-0877282686.