The chief mark and element of insanity… is reason used without root, reason in the void…. But we may ask in conclusion, if this be what drives men mad, what is it that keeps them sane? …[T]o give a general answer[:] Mysticism…
The ordinary man has always been sane because the ordinary man has always been a mystic…. He has always left himself free to doubt his gods; but (unlike the agnostic of to-day) free also to believe in them. He has always cared more for truth than for consistency. If he saw two truths that seemed to contradict each other, he would take the two truths and the contradiction along with them. His spiritual sight is stereoscopic, like his physical sight: he sees two different pictures at once and yet sees all the better for that. Thus he has always believed that there was such a thing as fate, but such a thing as free will also…. It is exactly this balance of apparent contradictions that has been the whole buoyancy of the healthy man. The whole secret of mysticism is this: that man can understand everything by the help of what he does not understand.
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….
Like the sun at noonday, mysticism explains everything else by the blaze of its own victorious invisibility–Detached intellectualism is (in the exact sense of a popular phrase) moonshine; for it is light without heat, and it is secondary light, reflected from a dead world… Of necessary dogmas and a special creed I shall speak later. But that transcendentalism by which all men live has primarily much the position of the sun in the sky. We are conscious of it as of a kind of splendid confusion; it is something both shining and shapeless, at once a blaze and a blur. But the circle of the moon is as clear and unmistakable, as recurrent and inevitable, as the circle of Euclid on a blackboard. For the moon is utterly reasonable; and the moon is the mother of lunatics and has given to them all her name.
A stunning quote from G.K. Chesterton’s Orthodoxy, pp. 17-19. I have argued here and here that rationality as the main or only measure of humanity is both insufficient and potentially dangerous… and the idea that mysticism keeps us sane – I would argue keeps us human – is especially meaningful for those of us in the arts.