Liber AL vel Legis, commonly known as The Book of the Law, is the central sacred text of Thelema. Written by Aleister Crowley, with his wife Rose Edith Kelly who wrote two phrases into the finished manuscript, Crowley claimed it was dictated to him by a preternatural being calling himself Aiwass. The book's three chapters are largely written in a first-person narrative by the Thelemic deities Nuit, Hadit, and Ra-Hoor-Khuit respectively.
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 "Æon of Horus".The primary precept of this new aeon is the charge to "Do what thou wilt shall be the whole of the Law".
The book contains three chapters, each of which was alleged to be written down in one hour, beginning at noon, on 8 April, 9 April, and 10 April in Cairo, Egypt, in the year 1904.Crowley says that the author was an entity named Aiwass, whom he later referred to as his personal Holy Guardian Angel.