Iranian libraries hold only few manuscripts that testify to the extended and intensive Mu'tazilite past in the various centers of Zaydi scholarship in the Caspian region, in Hurasan, and in Rayy. Among the few Mu'tazilite Zaydi works preserved in the libraries of Iran is a miscellany held by the library of the Faculty of Medicine at the University of Shiraz (‘Allama Tabataba'i Library). The maGmu'a, a facsimile of which is included in the present publication, was written between 673/1274-75 and 676/1277 and contains doctrinal works by Imami and Zaydi theologians from both Iran and from Yemen. Most of the codex consists of a theological summa, a ta'liq that had been composed or transcribed by one Abu Tahir b. 'Ali al-Saffar which was based on the Kitab al-Usul by Abu 'Ali Muhammad b. Hallad al-Basri, the distinguished disciple of the Mu'tazilite theologian and founder of the Bahsamiyya, Abu Hasim al-Gubba'i (d. 321/933), with an unknown number of commentary layers in between.