Ordo Templi Orientis (O.T.O.) ("Order of the Temple of the East", or the "Order of Oriental Templars") is an international fraternal and religious organization founded at the beginning of the 20th century. Originally it was intended to be modelled after and associated with Freemasonry, but under the leadership of Aleister Crowley was reorganized based on the Law of Thelema as its central religious principle along with "The Book of the Law". Similar to many secret societies, O.T.O. membership is based on an initiatory system with a series of degree ceremonies that use ritual drama to establish fraternal bonds and impart spiritual and philosophical teachings.