THE BREATH OF LIFE 



ball pitcher; he is made stronger up to the limit of 

 his capacity for strength. 



It is plain enough that all living beings are ma- 

 chines in this respect — they are kept going by the 

 reactions between their interior and their exterior; 

 these reactions are either mechanical, as in flying, 

 swimming, walking, and involve gravitation, or 

 they are chemical and assimilative, as in breathing 

 and eating. To that extent all living things are 

 machines — some force exterior to themselves must 

 aid in keeping them going; there is no spontaneous 

 or uncaused movement in them; and yet what a 

 difference between a machine and a living thing! 



True it is that a man cannot live and function 

 without heat and oxygen, nor long without food, 

 and yet his relation to his medium and environ- 

 ment is as radically different from that of the steam- 

 engine as it is possible to express. His driving- 

 wheel, the heart, acts in response to some stimulus 

 as truly as does the piston of the engine, and the 

 principles involved in circulation are all mechanical; 

 and yet the main thing is not mechanical, but vital. 

 Analyze the vital activities into principles of me- 

 chanics and of chemistry, if you will, yet there is 

 something involved that is neither mechanical nor 

 chemical, though it may be that only the imagina- 

 tion can grasp it. 



The type that prints the book is set up and again 

 distributed by a purely mechanical process, but that 



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