John, whose secular name was Mansur, was born in Damascus probably in the third quarter of the seventh century. His father and grandfather had been prominent in the fiscal administration of Syria, and it is believed that his father was in charge of the fiscal administration of the Umayyad Empire, with its capital in Damascus, in the latter decades of the seventh century. John received a good Hellenistic education and probably entered the service of the Caliph at Damascus in his father's footsteps. At some point—probably at the beginning of the eighth century, when the administration of the Umayyad Empire was put in the hands of Muslim officials—John resigned his post and became a monk in the Holy Land, according to a late tradition at the monastery of Mar Saba in the Judaean Desert (though it...