CHAPTER XLIX 

 HEALTH AND DISEASE 



Importance of health. Physical health is essential 

 to the greatest success and happiness of any individual. 

 Likewise, the prosperity of any community depends 

 upon the health of the community, which is the com- 

 bined health of its individuals. The preservation of 

 health, both individual and public, is an important duty. 

 In order to fulfill this duty, imposed upon each one of 

 us, it is necessary to understand the conditions which 

 make for disease as well as those which make for health. 

 The science of keeping the body in good health is 

 called hygiene. 



Health and disease. We already know that each 

 organ in the body has a special work to do. It is 

 also true that each tissue and even each cell, has certain 

 functions to perform. If the various activities of all 

 of the cells are being properly performed, we are in 

 good health. If anything, however, interferes with the 

 functions of these cells so that they are not properly 

 performed disease results. 



Cause of disease. Diseases are due to many causes, 

 some of which are known, and some of which are still 

 unknown. The causes of some diseases are very evi- 

 dent; for example, an accident may deprive a man of 



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