This book records the 781 A.D. dialogue between the third Abbasid Caliph, al-Mahdi, and Timothy I, the first Nestorian Patriarch in Baghdad, a city which, at the time, had become the seat of Muslim power. This volume is a slightly revised version of The Caliph al-Mahdi and the Patriarch Timothy I: An 8th Century Interreligious Dialogue. There are several alterations: the new font size makes for an easier read, and changes in style and content add clarity.