202 MIND AND BRAIN. 



probably never will know. However, for all practical 

 purposes, it is sufficient to know that, if we desire active 

 and vigorous minds, we must try to keep healthy brains; 

 we may then consider all the knowledge we can get 

 about the hygiene of the brain as coming, in the long- 

 run, to the same thing as hygiene of the mind. 



