Saint Isidore was born in Alexandria, Egypt, in the 4th century, the exact date of his birth is unknown. His parents were Christians, and among his relatives were two Patriarchs of Alexandria - Theophilus and Saint Cyril.
As a youth, Isidore withdrew from this world and went to Egyptian Mount Pelusium, where he labored as a monk. His great knowledge of human soul, along with wisdom and asceticism attracted other people who desired to live a monastic life. Isidore was elected as their abbot and ordained into priesthood.
While traveling to Constantinople (present-day Istanbul, Turkey) St Isidore met and heard the preaching of Saint John Chrysostom ("golden-mouth," name earned for eloquence in preaching). This encounter inspired Isidore to dedicate his efforts primarily to Christian preaching and teaching.
He never refused to give advice to all those who came to him looking for spiritual support - be it a simply man, a bishop, a patriarch of Alexandria, or even the emperor himself. Isidore wrote over 10,000 letters, however only 2,090 survived to our days (a few examples of such letters, in this instance to different monks, you can find here). Most of these letters contain a deep theological thought and morally edifying commentary of the Holy Scriptures.
St Isidore died peacefully in old age around AD 436. The Church historian Evagrius (6th century) wrote of Isidore, “His life seemed to everyone to be the life of an angel upon the earth.” Another historian, Nicephorus Callistus (9th century), praises Isidore for being “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.”
The image of God was truly preserved in you, O Father Isidore, for you took up the Cross and followed Christ. By so doing you taught us to disregard the flesh for it passes away, but to care instead for the soul, since it is immortal. Therefore your spirit, O venerable Isidore, rejoices with the angels.
Finding you to be another morning star, O glorious Isidore, the Church is illumined by the brilliance of your words. She cries out to you: “Rejoice, all-blessed and divinely-wise Isidore.”