The Risãla al-Jãmi'a ('The Comprehensive Epistle'), attributed to the anonymous Ikhwãn al-Safã?, is an important document in the history of philosophy, sciences, and religious thought in medieval Islamic civilization. Also known as 'The Crown of the Epistles of the Brethren of Purity', it represents the culmination of those 52 Epistles which constitute the oldest mediaeval encyclopaedia of sciences, thought to date from the 10th century. Yet, while following the main themes and four classificatory sections of the Rasã'il, the Jãmi'a distils rather than summarizes the content, delving further into esoteric topics and adopting a more distinctly Ismaili position. In support of their doctrine, the Ikhw?n marshal rational and textual evidence based on the Qur'an and scripture on the one hand and the works of Hellenic as well as Islamic philosophers on the other.

The present volume consists of Chapters 1-63 of the first half of the Jãmi'a, covering mainly the first section of the Ras??il (Riyãiyya ta 'limiyya, Propaedeutical-mathematical sciences) and including also an extended discussion on good and evil. This new critical edition draws on 20 manuscripts to establish a more reliable edition of the Arabic text. Translated here for the first time into English and copiously annotated, the work is elucidated by technical and analytical introductions.