He served as Prefect of Constantinople during the reign of the Emperor Theodosius. He was married and had two children, a son and a daughter. Despising their eminent worldly position, Nilus and his wife agreed to take up the monastic life in Egypt, she taking their daughter to a women's monastery, he taking their son to Mount Sinai. Together Nilus and his son Theodoulos lived in hesychia on the slopes of the mountain with the other monks, who spent their lives in solitude, only gathering once a week to partake of the Mysteries. One day some Saracen raiders attacked the monks, killing many and capturing others; Nilus' own son Theodoulos was among those taken. Nilus, to overcome his sorrow at losing his son, redoubled his prayers and ascetical labors, and became widely-known for his gifts of prophecy and discernment. He wrote more than a thousand letters and spiritual treatises, including some defending his spiritual father St John Chrysostom, who had been unjustly exiled.   After many years at Mt Sinai, St Nilus found his long-lost son alive. Father and son together were ordained to the priesthood by the Bishop of Elusas, who had been caring for Theodoulos. Saint Nilus reposed in peace around the year 430. His relics were later returned to Constantinople and venerated at the Church of the Orphanage.