CAUSES OF NERVOUS IMPAIRMENT 193 



who is said to have described it with great precision and 

 to have declared such persons to be "undesirable citi- 

 zens" for his republic. 



But the proportion of people who fall far below the 

 normal in courage and perseverence, in kindliness and 

 contentment is too large to allow us to say of every case 

 that the inheritance was much to blame. We must pass 

 on to the circumstances affecting the individual. These 

 may be divided into those which are strictly physical and 

 those which can be described as unfortunate mental 

 habits. Among the physical factors are some which are 

 bodily and some which are environmental. 



We may conveniently mention first disturbances of 

 nutrition. The opinion is commonly held that many 

 powerful personalities have been perverted by dyspepsia. 

 This is said, for example, of Carlyle. Of course, it is hard 

 in such instances to say which is cause and which is effect. 

 The indigestion may be the result of the inefficiency of a 

 nervous system in which pessimism is a congenital char- 

 acteristic. This is a difficulty of interpretation which we 

 constantly encounter in all discussions of this kind. But 

 whether despondency and cynicism are primary or sec- 

 ondary, there is no reasonable doubt that when they are 

 once established they continue to impair the digestive 

 capacity, and the alimentary trouble tends to intensify 

 the nervous deficiency. Thus, we have an illustration of 

 what is known to physicians as a "vicious cycle." 



The reaction of a disordered stomach and intestine 

 upon the brain is not solely by means of nerve-impulses 

 such as result in general sensation. It is now believed 

 that the influence exerted is largely due to chemical 

 products originating in abnormal fermentation processes 

 in the canal. Entering the blood, these deleterious com- 

 pounds are borne to all parts of the body, but they have 

 an especially marked effect upon the central nervous 

 system. The condition in which these poisons are circu- 

 lated and become productive of mischief is spoken of as 

 auto-intoxication. It is favored by overeating, especially 



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