THE ORIGIN OF LIFE 149 



gressive transmutation into phycocyanin, chlorophyll and the 

 blue-green algae. What value, then, have these conjectures? 

 If it be the function of natural science to discount actualities 

 in favor of possibilities, to draw arguments from ignorance, 

 and to accept the absence of disproof as a substitute for 

 demonstration, then the expedient of invoking the unknown 

 in support of a speculation is scientifically legitimate. But, 

 if the methods of science are observation and induction, if 

 it proceeds according to the principle of the uniformity of 

 nature, and does not utterly belie its claim of resting upon 

 factual realities rather than the figments of fancy, then all 

 this hypothecation, which is so flagrantly at variance with 

 the actual data of experience and the unmistakable trend of 

 inductive reasoning, is not science at all, but sheer credulity 

 and superstition. 



When we ask by what right men of science presume to 

 lift the veil of mystery from a remote past, which no one 

 has observed, we are told that the justification of this pro- 

 cedure is the principle of the uniformity of nature or the 

 invariability of natural laws. Nature's laws are the same 

 yesterday, to-day, and forever. Hence the scientist, who 

 wishes to penetrate into the unknown past, has only to "pro- 

 long the methods of nature from the present into the past." 

 (Tyndall.) If we reject the soundness of this principle, we 

 automatically cut ourselves off from all certainty regarding 

 that part of the world's history which antecedes human ob- 

 servation. Either nature's laws change, or they do not. If 

 they never change, then Spontaneous Generation is quite as 

 much excluded from the past as it is from the present. If, 

 however, as Hamann and Fechner explicitly maintain, nature's 

 laws do change, then, obviously, no knowledge whatever is 

 possible respecting the past, since it is solely upon the as- 

 sumption of the immutable constancy of such laws that we 

 can venture to reconstruct prehistory. 



The puerile notion that the synthesis of organic substances 

 in the laboratory furnishes a clue to the origin of organic 



