Every motor nerve must be balanced by an inhibitory nerve. The one furnishes the driving force, the other applies the brake. For instance, the heart muscle is supplied with motor force through the spinal nerves from the upper dorsal region, while the pneumogastric [vagus] nerve retards the action of the heart and in that way acts as a brake. Another brake is supplied by the waste products of metabolism in the system, the uric acid, carbonic acid, oxalic acid, etc., and the many forms of xanthines, alkaloids, and ptomaines. As these accumulate in the organism during the hours of wakeful activity, they gradually clog the capillary circulation, benumb brain and nerves, and thus produce a feeling of exhaustion and tiredness and a craving for rest and sleep. In this way, by means of the inhibitory nervous system and of the accumulating fatigue products in the body, Nature forces the organism to rest and recuperate when the available supply of vital force runs low. The lower the level of vital force, the more powerful will become the inhibitory influences. Now we can understand why stimulation is produced by paralysis. Stimulants precipitate the fatigue products from the circulation into the tissues of the body. They do this by overcoming and paralyzing the power of the blood to dissolve and carry in solution uric acid and other acids and alkaloids that should be eliminated from the organism. Thus will be explained more fully in the volume on "Natural Dietetics." Furthermore, stimulants temporarily benumb and paralyze the inhibitory nervous system. In other words, they lift the brakes from the motor nervous system, and allow the driving powers to run wild when Nature wanted them to slow up or stop. To illustrate: A man has been working hard all day. Toward night his available supply of vitality has run low, his system is filled with uric acid, carbonic acid and other benumbing fatigue products, and he feels tired and sleepy, At this juncture he receives word that he must sit up all night with a sick relative. In order to brace himself for the extraordinary demand upon his vitality, our friend takes a cup of strong coffee, or a drink of whisky, or whatever his favorite stimulant may be. The effect is marvelous. The tired feeling disappears, and he feels as though he could remain awake all night without effort. What has produced this apparent renewal and increase of vital energy? Has the stimulant added to his system one iota of vitality? This cannot be, because stimulants do not contain anything that could impart vital force to the organism. What, then, has produced the seemingly strengthening effect?