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.

About the year 626, the Persians, Avars, and Slavs came with a great host and besieged the imperial city of Constantinople while the Emperor Heraclius and the main body of the Byzantine army were absent in the East. Enemy ships filled the sea, especially the Golden Horn, and on land the adversaries were ready for attack with foot-soldiers, horses, and engines of war. Though the citizens courageously withstood them, yet they were few in number and would be unable to repulse the attack of such a great host. Hence, they could not count on any other means of salvation, except the protection of the Theotokos. And truly, suddenly a violent tempest broke up all the ships and submerged them, and the bodies of the invaders were cast out near the Blachernae quarter of the city where the famous Church of the Theotokos stood. Taking courage from this, the people went forth from the city and repulsed the remaining forces, who fled out of fear. In 673, the city was miraculously delivered yet again, this time from an invasion of the Arabs. Then in 717-718, led by the Saracen general Maslamah, the Arab fleet laid siege once more to the city. The numerical superiority of the enemy was so overwhelming that the fall of the Imperial City seemed imminent. But then the Mother of God, together with a multitude of the angelic hosts, appeared suddenly over the city walls. The enemy forces, struck with terror and thrown into a panic at this apparition, fled in disarray. Soon after this, the Arab fleet was utterly destroyed by a terrible storm in the Aegean Sea on the eve of the Annunciation, March 24, 718. Thenceforth, a special "feast of victory and of thanksgiving" was dedicated to celebrate and commemorate these benefactions. In this magnificent service, the Akathist Hymn is prominent and holds the place of honour. It appears that even before the occasion of the enemy assaults mentioned above, the Akathist Hymn was already in use as the prescribed Service for the Feast of the Annunciation, together with the kontakion, "When the bodiless one learned the secret command," which has the Annunciation as its theme. It was only on the occasion of the great miracle wrought for the Christian populace of the Imperial City on the eve of the Annunciation in 718 that the hymn "To thee, the Champion Leader" was composed, most likely by Saint Germanus, Patriarch of Constantinople.

Historians have ascribed the Akathist Hymn to Patriarch Sergius of Constantinople (638), to Saint George the Confessor, Bishop of Pisidia (818), or even to Saint Photius the Great (891), all of whom lived either at the time of or after the above-mentioned sieges. However, it appears most likely from its language, content, and style that the true composer of the Akathist Hymn is Saint Romanus the Melodist (6th century).

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.