104 THE POPULAR SCIENCE MONTHLY. 



but working at low-pressure is incomparably worse. As a matter of 

 experience, a sense of weariness commonly precedes collapse from 

 "overwork"; not mere bodily or nervous fatigue, but a more or less 

 conscious distaste for the business in band, or perhaps for some other 

 subject of thought or anxiety which obtrudes itself. It is the offensive 

 or irritating burden that breaks the back. Thoroughly agreeable em- 

 ployment, however engrossing, stimulates the recuperative faculty 

 while it taxes the strength, and the supply of nerve-force seldom falls 

 short of the demand. When a feeling of disgust or weariness is not 

 experienced, this may be because the compelling sense of duty has 

 crushed self out of thought. Nevertheless, if the will is not pleasura- 

 bly excited, if it rules like a martinet without affection or interest, 

 there is no verve, and, like a complex piece of machinery working with 

 friction and heated bearings, the mind wears itself away and a break- 

 down ensues. Let us look a little closely at this matter. 



The part which " a stock of energy " plays in brain-work can scarce- 

 ly be exaggerated. Reserves are of high moment everywhere in the 

 animal economy, and the reserve of mental force is in a practical sense 

 more important than any other. It may happen that mere strength of 

 mind carries a body with scarcely a vestige of power in reserve through 

 some crisis of extraordinary difficulty, but the mental exploit is full of 

 danger. The residual air in a lung is the basis of the respiratory 

 process ; the sustained tension of the smaller arteries transforms the 

 pulsating current of blood thrown into the system by the heart to a 

 continuous circulation ; the equilibriated tonicity of opposing muscles 

 gives stability to the apparatus of motion, and renders specific combina- 

 tions of movement possible. What is truq of the physical is also true 

 of the mental constitution ; the residual force, the tension, the tonici- 

 ty, of mind, form the basis of intellectual action. It is not necessary 

 to discuss the relations of mind and matter ; even if the mental being 

 is no more than a formulated expression of the physical organism, the 

 continuity is so complete that the same laws govern both. For the 

 purposes of the present argument it is sufficient to assert that, without 

 a reserve of energy, healthy brain-work is impossible. Pain, hunger, 

 anxiety, and a sense of mind-weariness, are the warning tokens of ex- 

 haustion extending to the reserves. When these indications are dis- 

 regarded, or destroyed, as they may be, by stupefying drugs, an inor- 

 dinate use of stimulants, a strong effort of the will, or the anaesthetic 

 effect of excessive exhaustion, the consumption of energy goes on un- 

 observed. The feats of intellectual or physical strength, the surprising 

 exploits of special sensation and mind-power, performed by individuals 

 under the influence of any condition which suspends the sense of pain, 

 weakness, or fatigue, are explained by the circumstance that unsus- 

 pected reserves of power and endurance are placed at the disposal of 

 the will. These resources were there before, but jealously guai'ded by 

 the sensations. Martyrdom is possible under the influence of an over- 



