A Comparative Study of Quṭb al-Dīn Shīrāzī's Texts and Models on the Configuration of the Heavens

This dissertation analyzes the astronomical writings of Quṭb al-Dīn Shīrāzī, a well-known Persian scholar of the Ilkhanid era (i.e., the second half of the thirteenth century to the early decades of the fourteenth century C. E.). The sustained attempts, by scientists of the Islamic world to rid Ptolemaic astronomy from what they considered its many non-physical characteristics was the driving force of the particularly productive genre of hay'a or the science of the configuration of the universe. All three of Shīrāzī's works that are studied in this thesis belong to this genre of astronomical writing. These works are the Nihāyat al-idrāk fī dirāyat al-aflāk (1281 C. E.), al-Tuḥfa al-shāhīya fī ‘ilm al-hay'a (1285 C. E.), and the Ikhtīyārāt-i Muẓaffarī. This thesis highlights Shīrāzī's models for the upper planets, and their evolution over the period 1281 to 1285 C. E. A careful look at the models for the upper planets allows for a clearer view of the distinctions between these three substantial works and their relations to one another. In particular this study allows us to date the Ikhtīyārāt-I Muẓaffarī to the same period as the Nihāyat al-idrāk fī dirāyat al-aflāk, i.e., c. 1281 C. E. In the thesis I discuss, as well, the reasons for Shīrāzī's choice of language for the Ikhtīyārāt-I Muẓaffarī, which was written in Persian (unlike the other two that were written in the lingua franca of Islamic science and scholarship, Arabic). This thesis demonstrates, as well, that the Ikhtīyārāt-I Muẓaffarī was a scientific work of the same technical sophistication as the other two works listed.