I am therefore not deeply worried by the fact that prayer is at present a duty, and even an irksome one. This is humiliating. It is frustrating. It is terribly time-wasting—the worse one is praying, the longer one’s prayers take. But we are still only at school. Or, like Donne, “I tune my instrument here at the door.” And even now—how can I weaken the words enough, how speak at all without exaggeration?—we have what seem rich moments. Most frequently, perhaps, in our momentary, only just voluntary, ejaculations; refreshments “unimplored, unsought, Happy for man so coming.”
But I don’t rest much on that; nor would I if it were ten times as much as it is. I have a notion that what seem our worst prayers may really be, in God’s eyes, our best. Those, I mean, which are least supported by devotional feeling and contend with the greatest disinclination. For these, perhaps, being nearly all will, come from a deeper level than feeling. In feeling there is really so much that is not ours—so much that comes from weather and health and from the last book read. One thing seems certain. It is no good angling for the rich moments. God sometimes seems to speak to us most intimately when He catches us, as it were, off our guard. Our preparations to receive Him sometimes have the opposite effect. Doesn’t Charles Williams say somewhere that “the altar must often be built in one place in order that the fire from heaven may descend somewhere else“?
– C. S. Lewis, Letters to Malcolm (Mariner Books ed), 116-117.