From Is Theology Poetry by Lewis

"If minds are wholly dependent on brains, and brains on biochemistry, and biochemistry (in the long run) on the meaningless flux of the atoms, I cannot understand how the thought of those minds should have any more significance than the sound of the wind in the trees. And this is to me the final test. This is how I distinguish dreaming and waking. When I am awake I can, in some degree, account for and study my dream. The dragon that pursued me last night can be fitted into my waking world. I know that there are such things as dreams; I know that I had eaten an indigestible dinner; I know that a man of my reading might be expected to dream of dragons. But while in the nightmare I could not have fitted in my waking experience. The waking world is judged more real because it can thus contain the dreaming world; the dreaming world is judged less real because it cannot contain the waking one. For the same reason I am certain that in passing from the scientific points of view to the theological, I have passed from dream to waking. Christian theology can fit in science, art, morality, and the sub-Christian religions. The scientific point of view cannot fit in any of these things, not even science itself. I believe in Christianity as I believe that the Sun has risen, not only because I see it, but because by it I see everything else." - C. S. Lewis, "Is Theology Poetry?"