Nestorius, Archbishop of Constantinople, stood strongly against the custom of calling Mary the Mother of God; his opponents led by Cyril of Alexandria, claimed that he denied that Jesus was God. He was condemned by the Council of Ephesus, deposed, and eventually sent into exile in Egypt. This dialogue, which he wrote in Egypt, replies to his adversaries; it is translated from the Syriac translation of which one manuscript was discovered in 1889 and disappeared in the First World War. Nestorius asserts that Jesus was truly God, truly man, and truly one; he condemns the doctrine associated with his name; he also condemns the doctrine of Cyril. Students of theology may differ on whether the doctrine of this book is orthodox; but all of them will find it an irreplaceable source on the Christology of the fifth century