"Contemplating is receiving." (St. John of the Cross) What we receive in prayer is the Spirit, who makes all creation new, moment by moment. It is the Spirit who rebirths us within the caves of our hearts. The case is a metaphor for this silent withdrawal, this going away to be alone, to listen, to gestate the Spirit, to rebirth ourselves. The reborn self is the child of wisdom born in solitude.
Angels are forms, images and expressions through which the essences and energy forces of God can be transmitted; and, since there are an infinite number of these forms, the greatest service anyone can pay the angelic host is never consciously to limit the ways angels might appear to us.