This volume contains a unique theological-philosophical text in Syriac known as the Book on the Knowledge of the Truth, or the Cause of Causes. In a conciliatory manner, the author, who purports to be a bishop of Edessa, deals with a variety of philosophical and theological topics. Writing perhaps in the tenth century, he offers the book as a “common book for all peoples under heaven” and its task is to teach how knowledge of the truth might be recognized. The editor, having discussed the manuscripts of the work in the introduction, presents the text in a handwritten script with a critical apparatus. A helpful index of proper names occurring in the book is also included. This work will be of interest to those who study philosophy, science, and theology in the middle east, as well as for students of inter-religious dialogue.