252 CONSERVATION OF ENERGY. 



to making heat, which, in this case, we do not desire. In 

 many machines there is great loss from friction, loss by ra- 

 diating heat, etc. Physiologists tell us that the human body 

 utilizes a larger portion of its energy than most machines. 

 While energy may fail to be used for the desired purpose, 

 it is never destroyed, nor really lost. 



" The proof of the facts just stated has led to the estab- 

 lishment of the grand twin conceptions of modern science : 



" 1. That all kinds of energy are so related to one another 

 that energy of any kind can be transformed into energy of 

 any other kind, known as the doctrine of the Correlation of 

 Energy. 



"2. That when one form of energy disappears, an exact 

 equivalent of another form of energy always takes its place, 

 so that the sum total of energy is unchanged, known as 4he 

 doctrine of the Conservation of Energy." 



These two principles constitute the corner stone of physical 

 science, and must be learned and kept in mind if we would 

 understand the actions of our bodies, and our relations to the 

 surrounding parts of the world and the universe in which we 

 live and of which we must consider ourselves a part. 



What is the object of this ceaseless change of nutrition 

 and growth ? Is it simply that the body may be nourished ? 

 Do we live to eat, or do we eat to live ? And what is it to 

 live ? Merely to be an animal, even the most highly devel- 

 oped on this earth ? 



" On earth there is nothing great but man. In man there 

 is nothing great but Mind." The muscles are the servants 

 of the will. These servants we have been studying. Let us 

 turn to the study of the Master Tissue, the central nervous 

 system. 



READING. See Appendix. 



