282 THE FITNESS OF THE ENVIRONMENT 



we possess. For these facts an explanation of 

 a different sort would be necessary, some- 

 thing logically resembling natural selection, 

 a natural process acting automatically through 

 the properties of matter and energy, and 

 never overstepping the limits of matter and 

 energy, space and time; neither supernatural 

 nor metaphysical, but purely mechanistic. 

 Lacking any indication of what such an expla- 

 nation may be, or how it is to be sought, we 

 shall do well to turn to other considerations. 



n 



VITALISM 



All the skill of trained biologists, multi- 

 plying and refining our knowledge of the 

 forms of life, has even yet not availed to make 

 clear the fundamental ideas of the science. 

 Complexity exists here in the very nature 

 of the case, and here, if at all, the complete 

 subjugation of natural phenomena to physi- 

 cal science may be expected to fail. 



In an earlier chapter the painful advance of 

 physics and chemistry into the domain of 

 biology has been sketched, and it was then 

 shown how progress is beset with well-nigh 

 insuperable obstacles. Thus it is that bio- 

 logical thought has never attained to that 



