First published in 1919, The Equinox: Volume III, Number I, also known as The Blue Equinox is essential reading for students of Thelema. Within its pages are instructions for initiates, including Aleister Crowley's own extensive reading lists divided into courses. The book also details the history, principles and aims of the secret society O.T.O. and its ally the A∴A∴, both of which were under Crowley's control at the time.

A trove of first-hand knowledge for initiates and those Thelemites who have advanced further, The Blue Equinox includes such topics as The Law of Liberty, The Gnostic Mass and the importance of The Book of the Law.