|The central teaching of Thelema is that every soul is eternal, and possesses a "True Will" or essential purpose that is the law under which it lives. During each incarnation, the soul seeks to find and accomplish its true will. Any action in harmony with one’s true will is good, whether or not it corresponds to ordinary ideas of morality, while every action not in harmony with one’s true will is wrong. In the standard Thelemite phrasing, "thou hast no right but to do thy will."
Another aspect of Thelemite belief has to do with cosmic cycles in which a succession of gods or ruling spiritual powers replaces one another at the helm of the cosmos. The writing of the Book of the Law, according to Thelema, marked the end of the Aeon of Osiris??"an age in which virtue consisted of sacrifice and self-abasement??"and the beginning of the Aeon of Horus, the age of the Crowned and Conquering child, in which will and the unabashed fulfillment of desires are the dominant themes. The aeons seem to be roughly equivalent to the twelve great months of the cycle of precession.
Most organized Thelemic activity at present is associated with the Ordo Templi Orientis (OTO). The Gnostic Mass, a ritual written by Crowley, is celebrated by most OTO groups as the principal public rite of Thelema