The Monk Isidore of Pelusium lived during the fourth-fifth centuries. He was a native of Alexandria, and was raised amidst pious Christians. He was a kinsman of Theophilos, Archbishop of Alexandria, and of his successor, Saint Cyril. While still a youth he quit the world and withdrew within Egypt to Mount Pelusiotes, which became the site of his monastic efforts. The spiritual wisdom and strict asceticism of the Monk Isidore, in combination with his broad erudition and innate knowledge of the human soul, allowed him in a short while to win the respect and love of his fellow monks. They chose him as their head and had him elevated to the dignity of presbyter.
Following the example of Saint John Chrysostom, whom he had managed to see and hear during the time of a journey to Constantinople, the Monk Isidore devoted himself primarily to Christian preaching – that “practical wisdom” which, in his own words, is both “the foundation of the edifice and the edifice itself,” while at the same time logic is “its embellishment” and contemplation – its crown.”
He was a teacher and a willing giver of counsel for anyone recoursing to him for spiritual encouragement: whether it be a simple man, a dignitary, a bishop, the Patriarch of Alexandria or even the emperor himself. He left after him about 10,000 writings, of which 2,090 have survived. A large portion of these writings are profound in theological thought and contain morally edifying interpretations of Holy Scripture. It is here that the Monk Isidore stands out as the finest disciple of Saint John Chrysostom. The love and devotion of the Monk Isidore for Saint John Chrysostom resulted in decisive acts in defense of Saint John during the time of his persecution by the empress Eudoxia and archbishop Theophilos. After the death of Saint John, the Monk Isidore persuaded Theophilos’ successor Saint Cyril to inscribe the name of Saint John Chrysostom into the Church diptychs as a confessor. And through the initiative of the Monk Isidore was convened the Third Ecumenical Council at Ephesus (431), at which was condemned the false teachings of Nestorius concerning the Person of Jesus Christ.
The Monk Isidore lived into old age and died in about the year 436. The Church historian Evagrius (sixth century) writes about the Monk Isidore, that “his life seemed to everyone the life of an angel upon the earth.” Another historian, Nicholas Kallistos (ninth century), praises the Monk Isidore thus: “He was a vital and inspired pillar of monastic rules and Divine vision and as such he presented a very lofty image of most fervent example and spiritual teaching.”