The natural life in each of us is something self-centered, something that wants to be petted and admired, to take advantage of other lives, to exploit the whole universe. And especially it wants to be left to itself: to keep well away from anything better or stronger or higher than it, anything that might make it feel small. It is afraid of the light and air of the spiritual world, just as people who have been brought up to be dirty are afraid of a bath. And in a sense it is quite right. It knows that if the spiritual life gets hold of it, all its self-centeredness and self-will are going to be killed and it is ready to fight tooth and nail to avoid that. — CS Lewis (from Mere Christianity)