On the periphery of the Roman empire, the sixth-century desert city of Gaza served as a crossroads between Palestine and Egypt. The nearby village of Tawatha was home to the thriving monastery of Abbot Seridos and the renowned anchorites Barsanuphius, known to the people as the Great Old Man, and his disciple John. The laity of the area looked to the monks for spiritual leadership, as did their brother monks, bishops, and religious leaders from as far away as Jerusalem and Constantinople. Having adopted a life of physical isolation, the monks communicated with others by letters, offering...