The close relation between emotion and muscular action has long been perceived. As Sherrington[158] has pointed out, “Emotion ‘moves’ us, hence the word itself. If developed in intensity, it impels toward vigorous movement. Every vigorous movement of the body ... involves also the less noticeable coöperation of the viscera, especially of the circulatory and respiratory. The extra demand made upon the muscles that move the frame involves a heightened action of the nutrient organs which supply to the muscles the material for their energy.” The researches here reported have revealed a number of unsuspected ways in which muscular action is made more efficient because of emotional disturbances of the viscera. Every one of the visceral changes that have been noted--the cessation of processes in the alimentary canal (thus freeing the energy supply for other parts); the shifting of blood from the abdominal organs, whose activities are deferable, to the organs immediately essential to muscular exertion (the lungs, the heart, the central nervous system); the increased vigor of contraction of the heart; the quick abolition of the effects of muscular fatigue; the mobilizing of energy-giving sugar in the circulation--every one of these visceral changes is _directly serviceable in making the organism more effective in the violent display of energy which fear or rage or pain may involve_. “Reservoirs of Power” That the major emotions have an energizing effect has been commonly recognized.[*] Darwin testified to having heard, “as a proof of the exciting nature of anger, that a man when excessively jaded will sometimes invent imaginary offences and put himself into a passion, unconsciously for the sake of reinvigorating himself; and,” Darwin[159] continues, “since hearing this remark, I have occasionally recognized its full truth.” Under the impulse of fear also, men have been known to achieve extraordinary feats of running and leaping. McDougall[160] cites the instance of an athlete who, when pursued as a boy by a savage animal, leaped over a wall which he could not again “clear” until he attained his full stature and strength. The very unusual abilities, both physical and mental, which men have exhibited in times of stress were dealt with from the psychological point of view by William James[161] in one of his last essays. He suggested that in every person there are “reservoirs of power” which are not ordinarily called upon, but which are nevertheless ready to pour forth streams of energy if only the occasion presents itself. These figurative expressions of the psychologist receive definite and concrete exemplification, so far as the physical exhibitions of power are concerned, in the highly serviceable bodily changes which have been described in the foregoing chapters.