The Christian admits that the universe is manifold and even miscellaneous, just as a sane man knows that he is complex. The sane man knows that he has a touch of the beast, a touch of the devil, a touch of the saint, a touch of the citizen. Nay, the really sane man knows that he has a touch of the madman. But the materialist’s world is quite simple and solid, just as the mad-man is quite sure he is sane. The materialist is sure that history has been simply and solely a chain of causation . . . Materialists and madmen never have doubts.