IN TR 01) UCTION. 3 



expense of animal vigor. Unless we give care to the matter 

 of exercise, the blood circulates too slowly, the appetite and 

 digestion are likely to become somewhat dull, and the whole 

 body suffers. 



In regard to any machine of man's invention we know that 

 we must keep it 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 work it too hard. Are not our bodies worth 

 equal care ? If some part of a machine 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 get a new stomach or lungs. 



In the deacon's " One-Hoss Shay," all the parts were equal 

 in strength and durability, so that it went to pieces 



"All at once, and nothing first, 

 Just as bubbles do when they burst." 



In our bodies, usually some organ is weaker than the others. 

 If this be true of one of the more important organs, the 

 heart, liver, stomach, lungs, kidneys, then the whole organ- 

 ism must stop, because no substitution can be made. Since 

 most of us inherit weakness of some organ, it behooves us to 

 find out what forms of disease have afflicted our ancestors, 

 and then to guard carefully the weakest part. A person may 

 be strong in all the organs but one, and yet break down ; 

 whereas a person apparently feeble, yet well balanced, may 

 live longer, and have much better health. In fact, great 

 strength is often a source of great weakness. If one has 

 powerful muscles, and overworks them, he may overstrain the 

 heart, and consequently break down. 



The student ought to have his hours for exercise just as 

 regularly as his hours for study ; and it is a matter of con- 

 gratulation that so many of our educational institutions insist 



