• 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, psychology, metaphysics, and theology, in addition to didactic fables.

    This volume provides an edition, translation, and notes to Epistle 3: ‘On Astronomia’, from the section on Mathematics. The content is a mixture of elementary astronomy and astrology, but it is not a beginner’s textbook; rather, the purpose is to use these disciplines for spiritual, moral, and soteriological guidance. Thus the Epistle uses the argument from design to show the necessity of a Creator who made this harmonious universe; the wondrous design is then employed by the authors as a paradigm for proper ethical, political, and even economic conduct. By no means typical of Islamic astronomical literature, Epistle 3 reveals a fascinating group operating during the early period of Islam, who sought to continue one of the esoteric strands of Hellenistic philosophy within an Islamic context, meshing astronomy, astrology, Platonic–Pythagorean philosophy, Qur’anic and Biblical quotations, and anecdotes from the lives of the Abrahamic prophets.