34 THE POPULAR SCIENCE MONTHLY 



ever happens or ever has happened of such character as to wholly 

 thwart and put to confusion the perfectly sober, the truly devout mind 

 of man. When in the future laborious science shall have made itself 

 and common humanity more fully and securely possessed of this truth, 

 then will Darwin's labors stand revealed in their true grandeur. 



Biologists are wont to say that evolution is now universally ac- 

 cepted. To see how far this is from true in a thoroughgoing sense, 

 one has but to recall that Alfred Eussel Wallace, the co-discoverer with 

 Darwin of natural selection, denies evolution for part of man; and that 

 an untutored, unbalanced woman, Mrs. Eddy, founds a religious cult, 

 one cornerstone of which is an implied denial of universal evolution, 

 which cult gets in a generation a larger following than any other 

 started in recent times. 



It is impossible to argue out the full case of the universality of or- 

 ganic evolution here. To do so would lead into the lowermost sub- 

 tleties of technical science and logical process. A few of its surface 

 strata must suffice for now. 



Go to history to learn about the development of great ideas in 

 physical science and you will see how, over and over again, this de- 

 velopment has run much the same course. Three distinctly character- 

 ized stages are seen in these developments. The first is that of intuitive 

 perception; of spontaneous, vague, fragmentary statement; of badly 

 jumbled observation and fancy, thoughtfulness and vagary, truth and 

 error. During this time scientific proof in the strict sense hardly ap- 

 pears at all. 



Then comes the stage of what might be called discursive demonstra- 

 tion. The advance of this beyond the first is enormous in both essen- 

 tials and consequences. Its greatest significance lies in the fact that 

 the mind's ability to distinguish between demonstrated truth and 

 possible truth has now found itself. The difference between generaliza- 

 tions and theories about nature that rest on objective experience, and 

 such as may possibly be true, though they have no experiential basis, 

 now begins to be clearly seen. 



Finally comes the third stage, fundamentally differentiated from the 

 second by the fact that the mind has at last grasped the vital meaning 

 of quantitative values in demonstration. Evidence is now no longer 

 primarily discursive and incidentally mathematical, but is essentially 

 quantitative as well as qualitative. This quantitative stage biology is 

 now barely on the threshold of. 



It was Darwin more than any other biologist who carried the idea 

 of evolution into the second of these three stages. Failure to grasp the 

 full significance of this forward step must mean failure to assign to 

 him his true place in the history of thought. 



It has been pointed out time and time again that the evolutionary 



