The volume contains critical editions of the extant parts of two hitherto unknown theological works by the Buyid vizier al-Sahib b. ‘Abbad (d. 385/925), who is well known to have vigorously promoted the teaching of Mu'tazili theology throughout Buyid territories and beyond. The manuscripts on which the edition is based come from Cairo Geniza store rooms. They consist of two manuscripts for each of the two texts-testimony to the impact of al-Sahib’s education policy on the contemporaneous Jewish community in Cairo. The longer treatise of al-Sahib of ca. 350/960, possibly his Kitab Nahj al-sabil fi usul al-din, appears to be the earliest Mu'tazili work preserved among the Jewish community. The second, briefer treatise also contains a commentary by 'Abd al-Jabbar al-Hamadani (d. 415/1025).