When I reached the concrete area, about 15 or 20 meters from the first row of chairs, I did not realize that there was a relatively high curb from the pavement to the crowd. My left foot came down into the air, because of the difference in height. The momentum, and the law of gravity discovered some time ago by Newton, caused me, when I took that false step, to plunge forward until I fell, in a fraction of a second, onto the pavement.