“Attention is the origin of faith, hope, and love, according to to Nicephorus the Solitary, a fourteeth-century monk of Mt. Athos,
Having banished every thought from this inner talking (for you can do this if you want to). give it the following short prayer: “Lord Jesus Christ, Son of God, have mercy on me––and force it, instead of all other thought, to have only this one constant cry within. If you continue to do this constantly, with your whole attention, then in time this will open for you the way to the heart which I have described. There can be no doubt about this, for we have proved it ourselves by experience.
Nicephorus the Solitary, Writings from the Philokalia On the Prayer of the Heart, pp 33-34, Nicephorus the Solitary was a monk who lived in the 13th century, in the troubled years of the Byzantine Empire’s slow decline. He authored a brief but invaluable text of spirituality that has become a classic, On Vigilance and the Guarding of the Heart.
The French philosopher Simone Weil said,
Vigilance is the path to Life Eternal. Thoughtlessness is the path to death. The reflecting vigilant die not. The heedless are already dead.