62 THE FITNESS OF THE ENVIRONMENT 



rences throughout the universe, and that they 

 are the normal result of cosmic evolution, does 

 not in any way modify the subsequent course 

 of the inquiry, there appears to be no loss of 

 logical security from its introduction. Mean- 

 while the evidence that the special phenomena 

 under discussion are probably the nowise ex- 

 ceptional outcome of the operation of general 

 laws, and not merely sporadic, cannot fail to 

 lend weight to whatever conclusions may 

 ultimately be reached. 



Obviously it is in the physical and chemical 

 attributes of these two compounds and their 

 constituent elements that we find very many 

 of the conditions which make life possible 

 upon the earth. They are material, provided 

 and mobilized automatically, out of which 

 living things undoubtedly can be formed. 

 Moreover if we limit our study to the physico- 

 chemical properties of water and carbonic 

 acid, and to the compounds of carbon, hydro- 

 gen, and oxygen, we shall greatly simplify our 

 problem. It cannot be denied that this re- 

 striction, no less than the earlier decision to 

 restrict the postulated characteristics of life 

 to complexity, regulation, and metabolism, is 

 sure to limit the inquiry, often perhaps in a 

 very unwelcome manner. On the other hand, 

 the gain in economy and security is once 



