But suppose that the centre is not its place, and that the reason of its remaining there is this necessity of indifference on the analogy of the hair which, it is said, however great the tension, will not break under it, if it be evenly distributed, or of the man who, though exceedingly hungry and thirsty, and both equally, yet being equidistant from food and drink, is therefore bound to stay where he is even so, it still remains to explain why fire stays at the extremities.