2 PHYSIOLOGY. 



Value of Knowledge. The out-of-door worker may 

 not suffer so much from ignorance in these matters. 

 From the character of his occupation, he is, to a certain 

 extent, obliged to obey Nature. He gets enough fresh 

 air. His bodily exertion generally brings a hearty appe- 

 tite, vigorous digestion, active circulation of the blood. 

 Still, he would greatly profit by knowing something of the 

 nature of his food, its wholesomeness or unwholesomeness. 

 The fact that he has fair health is no proof that he always 

 does the best thing. His natural mode of life may keep 

 him in tolerably good condition in spite of his violation of 

 certain laws; but he could undoubtedly learn how to 

 economize in the purchase, preparation, and proper com- 

 bination of foods. 



Importance of the Care of the Body. Any machine 

 of man's invention must be kept in good running order if 

 we would have it do good work, or last long. We must 

 keep a machine clean, well oiled, and not overtax it. Are 

 not our bodies worth equal care ? If some part of a ma- 

 chine is broken, we may replace it at moderate expense ; 

 but none of the vital organs can be replaced. We may 

 get a new mainspring for a watch, but we cannot obtain a 

 new stomach or lungs. 



Its Admirable Mechanism. Aside from the above 

 considerations the human body is worthy of study for its 

 own sake. Viewed simply as a mechanism, it is wonder- 

 ful. Each organ is so well adapted to its work, and all 

 the organs work so harmoniously through their connection 

 and control by the nervous system, that we never cease to 

 admire it. We admire a doll, or other toy, so ingeniously 

 constructed that it can move its eyes or walk a short time 

 after being wound up. But this live mechanism, which is 



