In theory, for example, sleep is a negative thing, a mere cessation of life. But nothing will persuade me that sleep is not really quite positive, some mysterious pleasure which is too perfect to be remembered. It must be some drawing on our divine energies, some forgotten refreshment at the ancient fountains of life. If this is not so, why do we cling to sleep when we have already had enough of it; why does waking up always seem like descending from heaven upon earth? I believe that sleep is a sacrament; or, what is the same thing, a food.
— G.K. Chesterton, Lunacy and Letters