The madman is not he that defies the world. The saint, the criminal, the martyr, the cynic, the nihilist may all defy the world quite sanely. And even if such fanatics would destroy the world, the world owes them a strictly fair trial according to proof and public law. But the madman is not the man who defies the world; he is the man who _denies_ it. Suppose we are all standing round a field and looking at a tree in the middle of it. It is perfectly true that we all see it (as the decadents say) in infinitely different aspects: that is not the point; the point is that we all say it is a tree. Suppose, if you will, that we are all poets, which seems improbable; so that each of us could turn his aspect into a vivid image distinct from a tree. Suppose one says it looks like a green cloud and another like a green fountain, and a third like a green dragon and the fourth like a green cheese. The fact remains: that they all say it _looks_ like these things. It is a tree. Nor are any of the poets in the least mad because of any opinions they may form, however frenzied, about the functions or future of the tree. A conservative poet may wish to clip the tree; a revolutionary poet may wish to burn it. An optimist poet may want to make it a Christmas tree and hang candles on it. A pessimist poet may want to hang himself on it. None of these are mad, because they are all talking about the same thing. But there is another man who is talking horribly about something else. There is a monstrous exception to mankind. Why he is so we know not; a new theory says it is heredity; an older theory says it is devils. But in any case, the spirit of it is the spirit that denies, the spirit that really denies realities. This is the man who looks at the tree and does not say it looks like a lion, but says that it _is_ a lamp-post. I do not mean that all mad delusions are as concrete as this, though some are more concrete. Believing your own body is glass is a more daring denial of reality than believing a tree is a glass lamp at the top of a pole. But all true delusions have in them this unalterable assertion--that what is not is. The difference between us and the maniac is not about how things look or how things ought to look, but about what they self-evidently are. The lunatic does not say that he ought to be King; Perkin Warbeck might say that. He says he is King. The lunatic does not say he is as wise as Shakespeare; Bernard Shaw might say that. The lunatic says he _is_ Shakespeare. The lunatic does not say he is divine in the same sense as Christ; Mr. R.J. Campbell would say that. The lunatic says he _is_ Christ. In all cases the difference is a difference about what is there; not a difference touching what should be done about it.