'I was in the schoolyard. We happened to be having a broad-jumping competition. I won the prize, even though I was small and frail. In fact, perhaps I won because I was so – I knew that I should have to use my brains. I situated myself so that Satan's Wind was at my back, and then timed my leap so that I left the ground during an especially powerful gust. The wind carried my little body through space like one of these petals. For a moment I was gripped by an emotion – part thrill and part terror – as I imagined that the wind might carry me away – that my feet might never touch the earth again – that I would continue to skim along, just above the ground, until I had circumnavigated the globe. Of course I was just a boy. I didn't know that projectiles rise and fall in parabolic curves. Be those curves ever so flat, they always tend to earth again. But suppose a cannonball, or a boy caught up in a supernatural wind, flew so fast that the centrifugal force (as Huygens has named it) of his motion around the earth just counteracted his tendency to fall?'