And, in fact, He shows much more of Himself to some people than to others — not because He has favourites, but because it is impossible for Him to show Himself to a man whose whole mind and character are in the wrong condition. Just as sunlight, though it has no favourites, cannot be reflected in a dusty mirror as clearly as in a clean one…. And if a man’s self is not kept clean and bright, his glimpse of God will be blurred—like the Moon seen through a dirty telescope.

- C S Lewis, Mere Christianity