In his Tenth Conference, St. John Cassian (ca. 360 – 433) tells us how he and his companion, Germanus, approached the man who was reputed to be at that time the holiest, oldest, and wisest Father of the Desert [during seven years in Egypt ca. 380-400]. In seeking a word of life they asked him specifically for a word on prayer. Adda Isaac responded to them most generously:
I must give you a word for contemplation. If you dutifully keep this word before you and learn to recollect it at all time, it will help you to mount to contemplation of high truth…The word is this: “O God, come to my assistance. O, Lord, make haste to help me.” [Ps.69]
Rightly has this verse been selected from the whole Bible to serve this purpose. It still suits every mood and temper of human nature, every temptation, every circumstance. It contains an invocation of God, a humble confession of faith, s reverent watchfulness, a meditation on human frailty, an act of confidence in God’s response, an assurance of his ever-present support. The one who continuously invokes God as his protector in aware that God is ever at hand.
I repeat: each to one of us, whatever one’s condition in the spiritual life, needs to use this verse.
Perhaps wandering thoughts surge about my soul like boiling water and I cannot control them. I cannot offer prayer without it being interrupted by silly images. I feel so dry that I am incapable of spiritual feelings. Many sighs and groans save me from dreariness. I must need say: “O God, come to my assistance. O Lord, make haste to help me.”
The mind should go on grasping this word until it can cast away the abundance and multiplicity of other thoughts and restrict itself to the poverty of a single word. And thus in will attain with ease that Gospel beatitude which states: “Blessed are the poor in spirit for theirs is the kingdom of heaven.” Thus by God’s light the mind mounts to the manifold knowledge of God and thereafter on mysteries loftier and more sacred.
John received from the lectio of a Spiritual Father a word of life, as well as a deep and beautiful sharing on the part of a Father who had already experienced the rich potential of this word in his own life.
From reading Lectio Divina – M. Basil Pennington (1998)