St. Mark was an ascetic and miracle-worker, sometimes known as Mark the Faster. In his 40th year he was tonsured a monk by his teacher, St. John Chrysostom. Mark then spent 60 more years in the wilderness of Nitria (a desert in Lower Egypt) in fasting and prayer, and in writing many spiritual works concerning the salvation of souls. He knew all the Holy Scriptures by heart. He was very merciful and kind, and wept much for the misfortunes that had befallen all of God's creation.
On one occasion, when weeping over a hyena's blind whelp, he prayed to God and the whelp received its sight. In thanksgiving the mother hyena brought him a sheepskin. The saint forbade the hyena in the future to kill any more sheep belonging to poor people. He received Communion at the hands of angels. His homilies concerned such topics as the spiritual law, repentance, sobriety, and are ranked among the preeminent literature of the Church. These works were praised by the Patriarch Photius the Great himself.
"Do not seek the perfection of the law in human virtues, for it is not found perfect in them. Its perfection is hidden in the Cross of Christ."