Agency and Effect in the Astrology of Abū Maʿshar of Balkh (Albumasar)

Abstract The aim of this paper is to show how the ninth-century astrologer, Abū Maʿshar Jaʿfar b. Muḥammad b. ʿUmar al-Balkhī, accounted for generation, corruption and change in the sublunary world. He sides with the philosophers against the astrologers and takes as his principal source the Peripatetic tradition. He shows that it is the movements of the heavenly bodies, rather than their elemental qualities, that are responsible for all elemental changes, and that these changes ‘result from,’ or follow naturally from, those movements rather than are caused by them.