The liturgy of the Eastern Orthodox Church is known and appreciated by the Catholic West. Less known are its non-liturgical devotions. One such devotion, ‘the prayer of Jesus,’ has for centuries been encouraged in the Eastern Church, though, leaving the freedom of choice in spiritual ways to her faithful, she never imposed it or ascribed to it any particular merits (a practice unknown to the East). With this proviso the Prayer can be compared with the Rosary in the West; and as its roots go back to the early, undivided Church, it could be claimed by the West no less than by the East.
‘Lord Jesus Christ, the Son of God, have mercy upon me, a sinner.’ This invocation has behind it volumes of spiritual writings and centuries of ascetico-mystical tradition. It is known as ‘the art or mental prayer.’
Many seem to have built their whole spiritual life on the prayer of Jesus, though it cannot be regarded as detached from the rest of the Christian life: Bible reading, sacramental grace, practice of the Commandments and theological virtues. In monasteries it was combined with special ascetical practices. Beginners in the use of the prayer abstained from devotional reading in order to concentrate, and the prayer replaced private psalmody in the cell, outside the services. Some kept it as a unique rule. It was repeated with beads several thousand times and was accompanied by prostrations. This acted as the first ascetical exercise of the will in obedience to the rule imposed by one’s spiritual father, teaching also control over the body.