The memory of this Saint is celebrated on March 30, where his biography may be found. He is celebrated today because his book, The Ladder of Divine Ascent, is a sure guide to the ascetic life, written by a great man of prayer experienced in all forms of the monastic polity; it teaches the seeker after salvation how to lay a sound foundation for his struggles, how to detect and war against each of the passions, how to avoid the snares laid by the demons, and how to rise from the rudimental virtues to the heights of Godlike love and humility. It is held in such high esteem that it is universally read in its entirety in monasteries during the Great Fast.

This Saint gave himself over to the ascetical life from his early youth. Experienced both in the solitary life of the hermit and in the communal life of cenobitic monasticism, he was appointed Abbot of the Monastery at Mount Sinai and wrote a book containing thirty homilies on virtue. Each homily deals with one virtue, and progressing from those that deal with holy and righteous activity (praxis) unto those that deal with divine vision (theoria), they raise a man up as though by means of steps unto the height of Heaven. For this cause his work is called "The Ladder of Divine Ascent." The day he was made Abbot of Sinai, the Prophet Moses was seen giving commands to those who served at table. Saint John reposed in 603, at eighty years of age. See also the Fourth Sunday of the Fast.

When Mary was only twelve years old, she left her parents and departed to Alexandria, where she lived a depraved life for seventeen years. Then, moved by curiosity, she went with many pilgrims to Jerusalem, that she might see the Exaltation of the venerable Cross. Even in the Holy City she gave herself over to every kind of licentiousness and drew many into the depth of perdition. Desiring to go into the church on the day of the Exaltation of the Cross, time and again she perceived a certain invisible power preventing her entrance, whereas the multitude of people about her entered unhindered. Therefore, wounded in heart by this, she decided to change her way of life and reconcile herself to God by means of repentance. Invoking our Lady the Theotokos as her protectress, she asked her to open the way for her to worship the Cross, and vowed that she would renounce the world. And thus, returning once again to the church, she entered easily. When she had worshipped the precious Wood, she departed that same day from Jerusalem and passed over the Jordan. She went into the inner wilderness and for forty-seven years lived a most harsh manner of life, surpassing human strength; alone, she prayed to God alone. Toward the end of her life, she met a certain hermit named Zosimas, and she related to him her life from the beginning. She requested of him to bring her the immaculate Mysteries that she might partake of them. According to her request, he did this the following year on Holy and Great Thursday. One year after this, Zosimas again went thither and found her dead, laid upon the ground, and letters written in the sand near her which said: "Abba Zosimas, bury here the body of wretched Mary. I died on the very day I partook of the immaculate Mysteries. Pray for me." Her death is reckoned by some to have taken place in 378, by some, in 437, and by others, in 522. She is commemorated also on the Fifth Sunday of Great Lent. Her life was recorded by Saint Sophronius of Jerusalem.