The Theologian and the Mathematician: Fakhr al-Dīn al-Rāzī and the Geometrical Works of Ibn al-Haytham

Fakhr al-Dīn al-Rāzī، theologian and philosopher of the 12th centuriy (1148-1209)، has a huge literary production in many scholary disciplines of his time. Nothwithstanding some original ideas which are mostly found in his theological and philosophical writings، most of his other works are compilations based on other sources. Some of these sources still exist، while most of the others seem to have been lost forever. Research on the the relation between al-Rāzī and his sources can explicate the way he chose his sources and the degree in which he transformed them. In this paper some of the mathematical themes borrowed by al-Rāzī from the works of Ibn al-Haytham، the great mathematician and physicist of the 10th – 11th century، are analysed and the way he has changed and adapted them to his purposes is discussed. This research can shed a light on the intellectual relations between different types of researchers – theologians، philosophers، and scientists of this important period in the intellectual history of the Islamic civilization. It can also show how the work of Ibn al-Haytham was received in the cultural domain of Iran almost one and a half century after his death.