THE BODY-MACHINE AND ITS WORK 



THE most perfect machine in the world is the body of man. 

 The further we advance in our knowledge of it, the more 

 we wonder at the ingenious mechanisms which are crowded 

 into its structure. Almost every decade we discover new opera- 

 tions in it which have a profound influence over our life, yet are 

 so subtle and unexpected that many generations of scientific men 

 were entirely ignorant of them, and it may take still many genera- 

 tions to tell how they bring about their marvellous results. Here, 

 as in other fields, the advance of science creates one mystery while 

 it explains another. But that story of evolution which we studied 

 in a preceding section sheds a clear light upon the body-machine 

 both of animals and of man, and enables us to understand the high 

 efficiency of most of its parts. The machine of the animal body 

 is not only the most perfect in nature ; it is immeasurably the old- 

 est. For at least fifty million years how much longer no man 

 knows the world-forces have been making the animal body, 

 developing and improving the various organs and co-ordinating 

 their functions. During all these tens of millions of years the 

 machine has been subject to the fiercest stresses and trials, and 

 the human body, as we know it, is the final and finished outcome. 

 We wonder no longer. Time itself makes nothing; but if we 

 grant a vast period of time to the real shaping forces of the uni- 

 verse, acting upon the most sensitive material in the universe, the 

 perfection of the final stage becomes intelligible. 



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