244 USE AND CARE OF THE NERVOUS SYSTEM 



ing and thinking, are also trained by the work which 

 we do with our muscles. This is especially true of the 

 early years, when the growth of nerve control is entirely 

 dependent upon physical activity. The apparently aim- 

 less kicking and tossing of a baby and the vigorous play 

 of young animals and children are nature's provision to 

 ensure the development of the nervous as well as of 

 the muscular system. 



Amount of work. Work, whatever its nature, should 

 not be continued after a certain degree of fatigue is 

 felt, since the more the nervous system is exhausted, 

 the more uncertain becomes its recovery during rest. 

 For this reason, periods of concentrated study should 

 be made short and be relieved by periods of rest and 

 recreation. The majority of the work should also not 

 be of so exacting a nature that the labor of holding 

 the attention to it is exhausting. The test in any case 

 of whether work is excessive, is the ability of the nerv- 

 ous system fully to recover from its effects by ordinary 

 sleep. 



Method of work. The way in which we do our work 

 is quite as important for the health of the nervous sys- 

 tem as its character and amount. The same piece of 

 work, whether mental or physical, may result in bene- 

 fit or harm. If we do it with a happy confidence that, 

 since we are doing our best, it must come out well in 

 the end, the effect upon the body and mind is one of 

 exhilaration and strength. The breathing is deeper, the 

 blood courses more vigorously through the vessels, the 

 brain gets a full supply, and every cell of the body is 

 in a condition to do its best work. If, on the contrary, 

 we do our work unwillingly, fretting lest it take too long 

 and not come out right in the end, the effect upon the 

 body and mind is one of depression. The tissues do not 



