The Book of the Law or Liber AL vel Legis is the central sacred text of Thelema, written down from dictation mostly by Aleister Crowley. Crowley claimed it was dictated to him by a discarnate entity named Aiwass. However, the three chapters are largely written in the first person by the Thelemic deities Nuit, Hadit and Ra-Hoor-Khuit.
The book contains three chapters, each of which was alleged to be written down in one hour in 1904, Cairo, Egypt.
Crowley believed that in order to discover the True Will, one had to free the desires of the subconscious mind from the control of the conscious mind, especially the restrictions placed on sexual expression, which he associated with the power of divine creation. He identified the True Will of each individual with the Holy Guardian Angel, a daimon unique to each individual. The spiritual quest to find what you are meant to do and do it is also known in Thelema as the Great Work.