Letters to Malcolm: Chiefly on Prayer.
Reflections on the Intimate Dialogue between Man and God.
Letter XII. Lewis talks about mysticism and how it is not for everyone. And, He give a couple of reason why it is easier to pray for others than for ones self.
Letter XIII. The issue of is anyone listening when we pray is tackled. Lewis proposes that sometimes what we say is, in some ways, God speaking to himself.
Letter XIV. “The soul that has once been waked … by the desire of God will inevitable … awake to the fear of losing him."