This is an exploration of the relationship between the rise and development of a mysical element in Islam, known as Sufism, and the mysticism that was already to be found within the Christian Church of the Near and Middle East, at the time when Arab power was establishing itself and the faith of Islam was in the process of formulation and development. In this earliest period of Islamic mysticism, the contacts between Christianity and Islam were at their closest. The book presents the mystics' teachings and allows their own writings to speak for them, to celebrate the shared devotion and inspiration of these two great religious traditions.