3Liber AL vel Legis, or The Book of the Law, is the central sacred text of Thelema. Crowley claimed it was dictated to him by a discarnate entity named Aiwass. Through the reception of the Book, Crowley proclaimed the arrival of a new stage in the spiritual evolution of humanity, to be known as the " on of Horus". The primary precept of this new aeon is the injunction to "Do what thou wilt".