80 THE POPULAR SCIENCE MONTHLY. 



Self-indulgent, luxurious habits, are highly injurious to healthy di- 

 gestion ; but on this threadbare subject it would be mere waste of time 

 to enlarge. Idleness, and the want of a definite pursuit in life, must 

 also rank high in this class of causes. To preserve the general health, 

 occupation is as necessary for the active mind as exercise is for the 

 vigorous body. 



The importance in the system of the reproductive functions is such 

 that their exhaustion must, sooner or later, react on the functions of 

 nutrition. Lamentable instances of the results of sexual excess are 

 occasionally met, and dyspepsia is almost invariably one of these. But 

 the injurious effects of a free indulgence of the sexual instincts have 

 been highly colored. Unprincipled men, who prey on the young and 

 the inexperienced, magnify and distort the significance of certain ail- 

 ments, the treatment of which, in too many instances, passes out of the 

 hands of the regular practitioner. 



In youth, the sensations are quickest, and the impressions most fresh 

 and vivid ; so that it might be supposed life would be always then 

 most keenly enjoyed. But its earlier years are frequently clouded. 

 An aching desire for change and excitement often destroys present 

 happiness ; and, when the desired excitement is unattainable, ennui and 

 a hopeless indolence ensue. Experience convinces me that this con- 

 dition of mind is but a frequent result of a feeble state of health. This 

 can be often traced to an overstrain of the mental powers a strain 

 daily increased among men by a spirit of emulation, fostered and re- 

 warded by the competitive system to an extent formerly unknown. 

 Accomplishments also among girls are made objects of relentless per- 

 severance. In both sexes, at a time when growth is incomplete, and 

 new functions are springing into existence, the mental are developed 

 at the expense of the bodily powers. Nutrition suffers because appe- 

 tite and digestion are impaired, and the power of the mind itself is 

 weakened. Over-exertion of mind fatigues equally with that of the 

 body. No reasonable doubt can therefore be entertained that thinking 

 is the result of a physical action in the brain. In what may be for con- 

 venience termed secretion of thought, demands are made on nutrition 

 just as in bodily exercise. It has been often observed that great 

 thinkers, if healthy, are usually large eaters. 



The state of the air we breathe is highly important in relation to 

 dyspepsia. We live at the bottom of an elastic medium, presenting 

 everywhere the same general composition, and exactly adapted to the 

 exigencies of animal life. Any accidental impurity of the atmosphere 

 tends to disturb the balance of health. Oxygenation of blood is the 

 object of respiration ; and its replenishment is the object of digestion. 

 On the other hand, the digestive secretions, as well as the nervous 

 energy by which they are governed, depend for their perfection upon 

 the perfect state of the blood. For this reason ill- ventilated workshops 

 and crowded sleeping-rooms among the poor, and the overheated and 



