BRAIN AND NERVOUS SYSTEM. 357 



or when they attend to a lecture or to a sermon in church, 

 especially in the summer, when their toil is the most ex- 

 hausting. This is a natural and necessary consequence. 

 The mind cannot have the use of the brain when it is occu- 

 pied with the restoration of exhausted physical power ; for 

 there is only a definite quantity of nervous energy, and, if 

 this is expended in muscular action, it is gone, and cannot 

 be given to mental labor. 



CHAPTER IX. 



Moral Feelings interfere with mental Action. Anxiety and Fear 

 prevent Attention to Business and Study. Fear, and misdirected 

 Hope, improper Motives for mental Action. Best Motive. 



822. THE mind cannot give its full and undivided atten- 

 tion to observation or reflection while it is distracted or 

 disturbed by any moral feeling. One who is anxious or in 

 fear cannot easily study. Hence some become confused, 

 and lose their self-possession, when they are in danger; they 

 do not then cencentrate their thoughts, and see clearly the 

 actual circumstances of their case, or the means of relief. 

 For the same reason, when one is riding with an ungovern- 

 able horse, he may not command his muscles in the best 

 way for his safety. Failing to perceive his true condition 

 and means of escape, so as to direct his movements to this 

 purpose, he may do the very things that increase.his peril. 



823. Anxiety absorbs much of the energy of the brain, 

 and prevents mental concentration ; consequently, one can- 

 not easily study, or give his mind to ordinary business, while 

 he is anxious for the -life of a parent or child, who is danger- 

 ously ill. For the same reason, when men devote themselves 

 to hazardous speculations, politics, or gambling, they often 

 neglect their usual engagements, and lose, not only the con- 

 fidence of their employers, but even the power of successfully 

 managing their customary affairs. 



