We actually had a custom bumper sticker made displaying the above exhortation and the names of the three books: Out of the Silent Planet, Perelandra, and That Hideous Strength.
My wife and I love the Space Trilogy — and Archbishop Chaput does, too! It makes the list in his article, “Ten ways to deepen our relationship with God.”
The archbishop says, “By the way, if you do nothing else in 2014, read Tolkien’s wonderful short story, Leaf by Niggle. It will take you less than an hour, but it will stay with you for a lifetime. And then read C.S. Lewis’ great religious science-fiction trilogy — Out of the Silent Planet, Perelandra and That Hideous Strength. You’ll never look at our world in quite the same way again.” — ARCHBISHOP CHARLES J. CHAPUT, O.F.M. CAP. http://www.catholiceducation.org/articles/Interiorlife/il0142.htm