Babai ‘the Great’, who died in 628, was a prominent figure in the history of the Church of the East during the long reign of Khosroes ii, in the course of the last years of the Sasanian Empire. In one of his works he conveniently left a list of his writings, and of those that survive the most important are the ‘Book of the Union’ (of the two natures in the incarnate Christ), an extensive commentary on Evagrius’ Kephalaia gnostica, and a long and informative narrative concerning the martyrdom of a high-ranking convert from Zoroastrianism, Mihramgushnasp, who was baptised with the name Gewargis. The few previous studies of Babai's writings have for the large part concentrated on those which concern Christology, seeing that his teaching on this topic remains authoritative in the Church of the East and so is important for modern ecumenical dialogue. While Engelmann, too, devotes a substantial chapter to Babai's writings on Christology, his other main concern (as his title suggests) is with the commentary on Evagrius’ Kephalaia gnostica, a work whose interest had been brought out by Antoine Guillaumont in his classic study of the history of Origenism in the Christian East. These two longer chapters are preceded by a sketch of the historical background and an outline of what is to be known of Babai's life. Other works by, or attributed to, Babai are also covered, and the Martyrdom of Gewargis is given particular attention. Engelmann's study, which originated as a Göttingen dissertation, makes good use of the available sources and serves to provide the reader with a clear and well-informed introduction to Babai and his surviving writings.