34 THE FITNESS OF THE ENVIRONMENT 



in truth we cannot otherwise conceive of life, 

 or indeed of any other durable mechanism. 

 For my part I do not doubt that these pos- 

 tulates are quite as true of the world of our 

 senses as are the fundamental laws of matter 

 and energy, space and time. 



Obviously these few conclusions can make 

 no claim to completeness. Fully to describe 

 life, the discovery of many other fundamen- 

 tal characteristics is necessary, including such 

 as are related to inheritance, variation, evo- 

 lution, consciousness, and a host of other 

 things. But in the formation and logical 

 development of such ideas there is danger 

 of fallacy at every step, and since the present 

 list will suffice for the present purpose, further 

 considerations of this sort are best dispensed 

 with. This subject should not be put aside, 

 however, without clear emphasis that the 

 postulates which have been adopted above 

 are extremely meager. The only motives for 

 abandoning further search are the economy 

 and the security which are thus insured, and 

 the very great difficulty of extending the 

 list. Any one who is familiar with similar 

 efforts to elucidate the essential character- 

 istics of life, such as that of Wallace, 1 cannot, 

 I fear, fail to perceive the extreme limitations 



1 A. R. Wallace, "Man's Place in the Universe." New 



