EIGIENE OF THE BRAIN. 311 



every-day language are called " habits": once we have repeat- 

 ed an action so often that our bodies almost unconsciously 

 do it, it becomes a habit, and needs special exercise of Will 

 to deviate from it. We thus find, in the tendency of the 

 nervous system to go on doing what it has been trained to 

 do, a physiological reason for endeavoring to form good 

 and to avoid bad habits of whatever sort, physiological, 

 business, social, or moral. Every thought, every action, 

 leaves in the nervous system its result for good or ill. The 

 more often we yield to temptation the stronger effort of 

 the Will is required to resist it. The knowledge that every 

 weak yielding degrades our nerve-organs and leaves its trail 

 in the brain, through whose action man is the "para- 

 gon of animals," while every resistance makes less close the 

 bond between the feeling and the act for all future time, 

 ought surely to "give us pause"; on the other hand, every 

 resistance of temptation helps to make subsequent resist- 

 ance easier. 



Hygiene of the Brain. The brain, like the muscles, is 

 improved and strengthened by exercise and injured by over- 

 work or idleness; and just as a man may specially develop 

 one set of muscles and neglect the rest until they degenerate, 

 so he may do with his brain; developing one set of intel- 

 lectual faculties and leaving the rest to lie fallow until, at 

 last, he almost loses the power of using them at all. The 

 fierceness of the battle of life nowadays especially tends to 

 produce such lopsided mental development. How often 



What happens when we have very frequently repeated an action? 

 Point out why it is desirable, even on physiological grounds, to form 

 good habits. How does every thought or act influence the nervous 

 system? What is the consequence of yielding to temptation? What 

 of resisting it? 



