Scholars studying the development of Imāmī thought are confronted with a lack of sources. Many pertinent works by Imāmī thinkers who lived in the various centers of Shīʿī learning between the lifetimes of al-Murtaḍā (d. 1044) and Naṣīr al-Dīn al-Ṭūsī (d. 1274) have not come down to us. Muʿtazilite thought, Avicennan notions, and the quest to return to the early doctrines...