"If the years of youth are experienced slowly, while the later years of life hurtle past at an ever-increasing speed, it must be habit that causes it. We know full well that the insertion of new habits or the changing of old ones is the only way to preserve life, to renew our sense of time, to rejuvenate, intensify, and retard our experience of time - and thereby renew our sense of life itself. That is the reason for every change of scenery and air."