Even a minimal acquaintance with the writings of al-Ghazzali gives the distinct impression that he was highly concerned with the threat the Ismailis and their doctrines posed against both himself and Sunni Islam. By his own admission, he wrote six separate treatises to refute and condemn them, most importantly his "The Infamies of the Esoterics" (Fada'ih al-batiniyya), which he composed in the year 488 (1095)-not in 487 (1094) as commonly stated-in the months prior to his famous renunciation of government service and departure from Baghdad. The new young Abbasid caliph al-Mustazhir had requested the work. While Ghazzali scholars have certainly taken careful note of various aspects of this treatise and there is one modern book devoted to it, the exact historical context that engendered it at the time, as well as various facets of Ghazzali's knowledge of Ismaili doctrine remain imperfectly understood. His attack on the doctrine known as ta?l?m, with its insistence on the unrivaled absolute authority of a single infallible imam, is a key piece of evidence until now not sufficiently explained. The assumption that he had in mind the Alamut teaching by Hasan-i Sabbah of what later came to be called Nizari Ismailism is correct but dating it to as early as 488 strongly suggests that it was a doctrine already widely advocated, at least in the Abbasid-Saljuk east, even prior to the Nizari-Musta?li split, which commenced only with the succession dispute that followed the death of the Fatimid caliph al-Mustansir. However, our knowledge of events in the career of Hasan and of his teachings come from much later sources and are fraught with problems. And they are in part legendary at best. Thus, although the doctrine of ta?lim, which was certainly implicit in Ismaili works long before, such as the Ikhtilaf usul al-madhahib of Qadi al-Nu?man, or various writings of al-Kirmani, in this particular work Ghazzali directed his attentions squarely against a teaching he encountered in his own time. We know it otherwise solely from imprecise accounts recorded much later. While his refutation deliberately renders that of his opponents weak and less than coherent-he has no incentive to fully and faithfully expound the doctrine of a heretical enemy-his is the earliest, and perhaps most complete, account of it available to us.