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.
The ordinary man has always been sane because the ordinary man has always been a mystic.

He has permitted the twilight.

He has always had one foot in earth and the other in fairyland.