THE DOGMA OF EVOLUTION 



mental reservation which, in fact, places him in the 

 class of dualists with one field of inquiry suppressed. 

 The physicist rigorously excludes from his field all 

 problems which involve life. For example; if he in- 

 vestigates the motion of a horse drawing a wagon he 

 does so by assuming that the earth pushes the horse 

 forward ; in other words, the horse is moved by an ex- 

 ternal mechanical force. He assumes that a horse can- 

 not by his will bend his legs and push against the 

 earth, and he refuses to consider whether it is alive 

 or whether it is a hobby-horse pushed by a child or 

 by a clock mechanism. If he finds such a mechanical 

 mechanism inside the horse he can investigate that 

 mechanism, but he has found 7io mechanical mechan- 

 ism inside the living organism which he can describe 

 as physical. The physicist has found no difference be- 

 tween the chemical constitution of matter when it is 

 living and when it is dead; he has found no relation 

 between mechanical energy and what we call life; he 

 has found no way of measuring thought or cell activ- 

 ity; for these reasons he excludes all life, and works 

 with a lifeless world. 



Now the biologists have invaded the world of the 

 physicist. They have invented a family tree, connect- 

 ing themselves genealogically with the physicist. 

 They call themselves biophysicists and biochemists 

 and claim a blood relationship. But they are not so 

 related; when they are studying living phenomena, 

 they are biologists; and when they are studying the 



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