Sort of sidetracked from the original topic ... Try to keep it on track, please.
IMO, the example of the car and screwjack is completely useless. I believe I've stated this before (maybe not, my mind might be playing tricks on me), but bare metal is a poor substitute for the human body.
Oh well, fair enough, let's drop it. Although I tend to think that an expanding groundpath is quite a bit like an expanding screwjack, what do I know?