The whole mechanism of this world is action and reaction, in the objective world as well as in the world of men. Only, in man there is the possibility of developing that spirit which is called the spirit of mastery, and that spirit is best developed by trying to gain control over one's reactions. Life offers us abundant occasions from morning till evening to practice this lesson. Every move, every turn we make, we are faced with something agreeable or disagreeable, harmonious or inharmonious, either a condition or a person. If we react automatically we are no better than a machine and no different from thousands and millions of people who do so. The only way to find in ourselves a trace of that divine heritage which is mastery, is by controlling our reactions against all influences. In theory it is simple and easy; in practice it is the most difficult thing there is to master. But when we think of its usefulness we shall find that there is nothing in the world that is more necessary and more important than this development. If there is any strength to be found in the world, that strength is within ourselves; and the fact that we are able to control our reactions is the proof of this. It preserves dignity, it maintains honor; it is this which sustains respect and it is this which keeps men wise; it is easy to think, but it is difficult to continue to be a thoughtful person.