Prayer of the Heart
This is the first time Our Lady mentions the 'Prayer of the Heart' in the course of the Thursday messages. Later on, she will call us to this form of prayer, her way of praying many times. In our struggle against Satan, our Blessed Mother wishes to train us in this kind of prayer, truly active and powerful prayer, which will become our standard weapon to overcome the power of Satan.
The early Christian Fathers, especially in the East, called it the 'prayer of watchfulness' (Cf. Luke 21:36; Ephesians 6:18; Colossians 4:2-4). Later on, especially in the Eastern (Orthodox) Churches, the 'Prayer of the Heart' became a standard terminology for deep prayer, the unceasing prayer, in the form of the Jesus Prayer for instance ("Lord Jesus Christ, have mercy on me a sinner.").
Such an all-involving prayer as the Prayer of the Heart unites us with Jesus and with our Blessed Mother so deeply that we may say with St. Paul: "It is no longer I who live, but Christ lives in me..." (Galatians 2:20). The Prayer of the Heart will be indeed the very means of surrendering ourselves completely to Jesus, and being protected from the Evil One, because Jesus himself will be our armour (Romans 13:14).