Perelandra

I just finished reading C.S. Lewis's Space Trilogy, and my first question is: Why are these three books so obscure? Everyone knows about Narnia, but how many are familiar with the fairy tales he wrote for adults? Out of the Silent Planet, Perelandra, and That Hideous Strength are meant for adults because they are so deep--so very, very deep-- and must be read as much with one's spirit as with one's mind. Lewis was a genius. If I could talk to him I would say, "Thank you for putting me in mind of the heavens. I will never be quite the same."