Imagination does not breed insanity. Exactly what does breed insanity is reason. Everywhere we see that men do not go mad by dreaming. Critics are much madder than poets.

To accept everything is an exercise, to understand everything is a strain. The poet only asks to get his head into heavens. It is the logician who seeks to get the heavens in his head. And it is his head that splits.

We may say in summary that it is reason used without root, reason in the void. The man who begins to think without the proper first principles goes mad; he begins to think at the wrong end. And for the rest of these pages we have to try and discover what is the right end. But we may ask in conclusion, if this be what drives men mad, what is it that keeps them sane?

By the end of this book I hope to give a definite, some will think a far too definite, answer. But for the moment it is possible in the same solely practical manner to give a general answer touching what in actual human history keeps men sane.

Mysticism keeps men sane.

As long as you have mystery you have health; when you destroy mystery you create morbidity. As we have taken the circle as the symbol of reason and madness, we may very well take the cross as the symbol at once of mystery and of health. For the circle is perfect and infinite in its nature; but it is fixed for ever in its size; it can never be larger or smaller. But the cross, though it has at its heart a collision and a contradiction, can extend its four arms for ever without altering its shape. Because it has a paradox in its centre, it can grow without changing. The circle returns upon itself and is bound. The cross opens its arms to the four winds; it is a signpost for free travellers.