Our minor morbidities, or sulky vanities and malicious self-righteousness

From Lunacy and Letters by G.K. Chesterton.

It is indeed, an absurd exaggeration to say that we are all mad, just as it is true that we are none of us perfectly healthy. If there were to appear in the world a perfectly sane man, he would certainly be locked up. The terrible simplicity with which he would walk over our minor morbidities, or sulky vanities and malicious self-righteousness; the elephantine innocence with which he would ignore our fictions or civilization—these would make him a thing more desolating and inscrutable than a thunderbolt or a beast or prey. It may be that the great prophets who appeared to mankind as mad were in reality raving with an impotent sanity.