St Mark was a disciple of St John Chrysostom, tonsured a monk at the age of forty by St John himself. He then withdrew to the Nitrian desert and lived for sixty years as a hermit, devoting himself to fasting, prayer, and writing spiritual discourses.
  Saint Mark knew all the Holy Scriptures by heart. His compassion was so great that he wept at the distress of any of God's creatures: once he wept for the blind pup of a hyena, and the pup received its sight. Though he lived alone in the desert, it is said that he received Communion from an angel.
  The holy and scholarly Patriarch Photios held his writings in the highest esteem, and at one time there was a saying, 'sell all that you have, and buy Mark.' Some of these beautiful and profound writings may be read in English in the first volume of the Philokalia.