One night in the year 411/1021, the powerful ruler of the Fatimid empire, al-Hakim bi-Amr Allah, rode out of the southern gates of Cairo and was never seen again. Was the caliph murdered, or could he have decided to abandon his royal life, wandering off to live alone and anonymous? Whatever the truth, the fact was that al-Hakim had literally vanished into the desert. Yet al-Hakim, though shrouded in mystery, has never been forgotten. To the Druze, he was (and is) God, and his disappearance merely indicated his reversion to non-human form. For Ismailis, al-Hakim was the sixteenth imam,...

The Ikhwan al-Safa (Brethren of Purity), the anonymous adepts of a tenth-century esoteric fraternity based in Basra and Baghdad, hold an eminent position in the history of science and philosophy in Islam due to the wide reception and assimilation of their monumental encyclopaedia, the Rasa'il Ikhwan al-Safa (Epistles of the Brethren of Purity). This compendium contains fifty-two epistles offering synoptic accounts of the classical sciences and philosophies of the age; divided into four classificatory parts, it treats themes in mathematics, logic, natural philosophy,...