G.K. Chesterton

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 madman is quite sure he is sane.
- G.K. Chesterton, Orthodoxy, 1908