Secret Arab brotherhood founded in Basra, Iraq, in the 10th century.
The beliefs of the group diverged sharply from orthodox Islam, incorporating elements of Neoplatonism , Gnosticism , astrology , and the occult sciences. The brotherhood is best known for having produced a philosophical and religious encyclopedia, Epistles of the Brethren of Purity and Loyal Friends , whose purpose was to provide enlightenment that would purify the soul and provide happiness in the next life.