Second, the shape of a key is in itself a rather fantastic shape. A savage who did not know it was a key would have the greatest difficulty in guessing what it could possibly be. And it is fantastic because it is in a sense arbitrary. A key is not a matter of abstractions; in that sense a key is not a matter of argument. It either fits the lock or it does not. It is useless for men to stand disputing over it, considered by itself; or reconstructing it on pure principles of geometry or decorative art. It is senseless for a man to say he would like a simpler key; it would be far more sensible to do his best with a crowbar. And thirdly, as the key is necessarily a thing with a pattern, so this was one having in some ways a rather elaborate pattern. When people complain of the religion being so early complicated with theology and things of the kind, they forget that the world had not only got into a hole, but had got into a whole maze of holes and corners. The problem itself was a complicated problem; it did not in the ordinary sense merely involve anything so simple as sin. It was also full of secrets, of unexplored and unfathomable fallacies, of unconscious mental diseases, of dangers in all directions. If the faith had faced the world only with the platitudes about peace and simplicity some moralists would confine it to, it would not have had the faintest effect on that luxurious and labyrinthine lunatic asylum. What it did do we must now roughly describe; it is enough to say here that there was undoubtedly much about the key that seemed complex; indeed there was only one thing about it that was simple. It opened the door.