Lord Jesus Christ, Son of God, have mercy on me, a sinner. This simple prayer has such a powerful meaning. Throughout history, the Jesus Prayer has been used for a variety of reasons, but it biggest purpose is to fulfill the Apostle Paul's call for unceasing prayer. This absolute beg for mercy becomes not only our prayer but even our breath as we begin to pray it constantly. There is nothing to learn, nothing hard to memorize, and no training needed; just the beauty and simplicity of a single sentence, a plea for mercy.
The Jesus Prayer finds it's roots in Luke's Gospel. The prayer is a combination of the Annunciation to Mary (Luke 1:31-35) and the parable of the Pharisee and the Publican (Luke 18:9-14). The prayer is a direct focus to God. There is no forms of self-repentance in the Jesus Prayer, but instead it is a plea to Christ for his perfect mercy. This plea is not only for mercy for ourselves, but for all of mankind. This begins not with us and the people we know, but with Adam, our first father. We are praying for mercy for even the sin of Adam.
Although this prayer comes from our Eastern Orthodox and Catholic fathers, there is a place for the Jesus Prayer in Western Christianity. In the East, this prayer is a bringing of monastic prayer into the lives of non-monastics. It focuses on the way the monastic fathers prayer, allowing yourself to have a direct encounter with Christ. To bring this prayer into our Western forms of prayer, we can have this same encounter. We can bring the Jesus Prayer into our own forms of meditative prayer, specifically in Eucharistic Adoration. We know we have a face-to-face encounter with Christ in the Eucharist, so why not encounter Christ in the Jesus Prayer while face-to-face with him in Adoration.
The spiritual function of the prayer is twofold. The first is perfect worship of Christ. We use the Jesus Prayer to not only encounter Christ but give him due worship, praise, and adoration. The second function is discipline of the mind. The focus and meditation of the prayer allows our souls to take control, calming our brains, and creating a stillness with the Holy Spirit. This stillness allows the Spirit to take an active role in our lives, working through us to create virtue in our lives.
Although the Jesus Prayer is simple, we cannot allow this to fool us. The prayer is not easy. The practice of the prayer in asceticism requires not only time and practice, but perseverance. To allow ourselves to come into communion with God in His grace takes patience as with any form of spiritual exercise. I will leave you with words from Elder Paisios of Mount Athos on the Jesus Prayer.
"In this way we will say the Jesus Prayer many times with our whole heart and we will feel, as I mentioned, the sweetness of divine comfort of the most sweet Jesus within our heart. The heart will then have our nous (soul) in tight embrace, as well as our whole being. Then, and only then, will prayer not be tiring, but rather it will give rest, because we have grasped the true meaning of it. Only then do we pray without putting pressure on ourselves, but we are pressurized by our sense of honor and dignity, which gives rise to all our spiritual upstanding generosity. This produces the fluttering of the heart. Then the heart (however stony it may be) breaks and tears burst forth from their ducts. You feel the need for this prayer like a hungry baby who opens its little mouth and runs into the arms of its mother to be suckled and at the same time feels very secure in its mothers loving care."
Господи Иисусе Христе, Сыне Божий, помилуй мя, грешнаго.