Isidore of Pelusium was a 4th and 5th-century ascetic monk and abbot who lived in Egypt. Born into a prominent family in Alexandria, he chose to flee the city to avoid being appointed as its Patriarch, instead seeking a life of solitude and discipline near Pelusium. Following the tradition of the Desert Fathers, he became a respected monastic leader. He is widely recognized for his extensive correspondence, which includes thousands of short letters addressing matters of theology, monastic rules, and moral guidance for various people.