SOME LESSONS ON THE HUMAN BODY 9 



In some cases this is by direct act of the will (mind) 1 , and 

 in other cases such as movements of the muscles of the heart, 

 diaphragm, and intestines, the action is largely or wholly 

 involuntary. It is over the nerves, too, that impulses 

 travel to the brain and other nerve centres giving rise to sensa- 

 tions. Education as "mind development" involves for one 

 thing an increasing readiness in interpreting correctly the 

 significance of sensations. 



SUMMARY 



Any study of the mouth cavity must take into account that it is a 

 part of the digestive tract, and a chief organ of speech. It is likewise 

 the chief gateway whereby germ diseases enter the body. The senses 

 of taste and smell may be considered as primarily for the purpose of 

 preventing entrance of injurious and poisonous substances into the 

 body with the food and drink, or with the air breathed. 



While the tongue as an organ of speech at times may be "an unruly 

 member," its muscles are nevertheless wholly subject to one's control. 

 Its utterances are what we make them. In learning to speak a foreign 

 language there is much the same difficulty experienced in getting the 

 muscles of the tongue to give correct utterance to sounds as there 

 is in bringing under control those of the hand when learning to play 

 musical instruments in correct time and with suitable expression. 

 Sustained and close attention, and much practice, may be necessary 

 to properly co-ordinate mind, nerve, and muscular action. 



1 No one is likely to mistake an electric light bulb for the electricity by 

 means of which the mechanism of the bulb produces the illumination. Nor is 

 there any confusion in distinguishing between a dynamo as a machine, and 

 the electrical energy sent out from it. In a similar manner a sharp distinction 

 is to be made between the brain as the organ of the mind on the one hand, and 

 on the other its powers (activities) in interpreting sensations, in noting rela- 

 tionships among these sensations, and in deciding upon a course of action in 

 accordance with the knowledge possessed. Whatever the nature of the brain 

 activity in the processes of thought, and however dependent mental vigor 

 may be upon a well-nourished brain, it simplifies our discussions here to con- 

 sider the mind, and the development and use of its powers, more or less apart 

 from brain phenomena. 



