Like the surface of inflated balloon, there is a tautness and lack of slack that comes from everywhere on the surface, so everywhere you touch the balloon you feel the integrity of that pressure. But if you were to put a hole in the balloon anywhere, anywhere at all, this nice tautness is gone, the balloon is now a deflated piece of rubber. One little gap in your all-sided support, and your profoundly neutral body is for crap, it is no longer profoundly neutral.
Of course, it doesn't make us invincible.
A little pin might do.