Modern exponent of ceremonial magic. Crowley was a product of the late- 19th-century magic revival which assumed that there was an invisible power, analogous to the “magnetic” power discussed by the mesmerists, that was the agent of magical operations. He later developed his own system of magical theory and practice, which he termed thelema (from the Greek word for will). He defined magic (which he usually spelled magick) as the art of producing change in the world using the universe’s underlying cosmic power through an intentional act of the will.
Two events largely gave structure to Crowley’s life after he left the hermetic order of the golden dawn, the organization that introduced ceremonial magic to him. In 1909, in Cairo, Egypt, he received a document called The Book of the Law through automatic writing from an entity called Aiwass. The Book of the Law included the basic principles of thelemic magic, including its definitive statement, “Do what thou wilt shah be the whole of the law.” This statement, often misunderstood as a license to do whatever one wanted to, is interpreted by thelemites as a call to discover one’s destiny (or true will) in life and then to subordinate everything else in life to the fulfillment of that destiny.