Archimedes said, "Give me a lever long enough, and a prop strong enough, and with my own weight I will move the world." "But," says Dr. Arnott, "he would have required to move with the velocity of a cannon-ball for millions of years, to alter the position of the earth a small part of an inch. This feat of Archimedes is, in mathematical truth, performed by every man who leaps from the ground; for he kicks the world away from him whenever he rises, and attracts it again when he falls."