Gravity is weird. On the one hand, gravity is a good thing, because it keeps me from floating away into space and makes possible my building stable shelters from the storm. On the other hand, gravity is a major cause of natural evil, as when buildings collapse during earthquakes or people fall through cracks in the ice and drown. The quirky American businessman, Roger Babson, was so alarmed by the evil consequences of gravity that in 1948 he founded the Gravity Research Foundation in New Boston, New Hampshire with the explicit aim of understanding gravity so as to defeat it. So how does gravity work? What keeps my feet planted firmly on the ground but then sends me tumbling painfully to the earth when I trip over a rock?

Aristotle on Free Fall