Nilus of Sinai was a 5th-century monk, theologian, and ascetic writer who served as an abbot. Originally a married layman and eparch of Constantinople, he was a devoted follower of John Chrysostom. Following the influence of his mentor, he and his wife eventually entered monastic life. After a period of searching for his son, who had been taken captive by raiders, Nilus lived as a hermit in a cave on Mount Sinai for forty years. He became a highly respected figure throughout the Eastern Church, providing counsel to individuals ranging from commoners to emperors.