208 MENTAL EXERCISE. 



of active growing muscles and hard-worked nervt>us 

 systems. The attempt to make them do so, is very apt 

 to stunt and injure both. As we grow older, and the 

 demands of the body for extra materials for its growth 

 become less or cease, more steady and continued brain- 

 work can be undertaken with safety and benefit. 



The " soundness" of the sleep is important. Five or 

 six hours of thorough deep sleep, with no dreams or 

 consciousness of any kind, are better than eight or nine 

 hours of uneasy sleep. Sleepnessness (insomnia) is a 

 very serious matter; if continued or frequent, medical 

 advice should be obtained. Unless checked, it leads to 

 exhaustion of the brain, and impairment of the mind. 



6. The Brain Needs Exercise. If the body in general 

 is healthy, the involuntary nerve-centres will look after 

 their own work, and take proper exercise and rest ; but 

 the part of the brain concerned with mental work is 

 more under our control, and may be harmed by over- 

 work or idleness. It is made stronger, and the mind 

 more vigorous, by regular exercise. 



When one first begins to train his muscles to do any 

 special task, they soon tire, but after a time the work 

 becomes easy, and more difficult feats can be under- 

 taken. In like way, mental work is apt at first to be 

 very fatiguing, but regularly repeated, with proper in- 

 tervals of rest, it becomes easier every time; and soon 

 harder tasks can be accomplished, and even enjoyed. 



trying to work hard with both brain and muscles ? What is said of 

 sound sleep as compared with restless ? Of sleeplessness? 



6. What do the involuntary nerve-centres do in health ? What 

 part of the nervous system is more in our control ? What is the 

 effect of exercise on the mind? What is the result of training the 

 muscles? The mind? What is said of the effects of idleness on the 

 mind? 



