Page:Popular Science Monthly Volume 76.djvu/38

34 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 accepted. To see how far this is from true in a thoroughgoing sense, one has but to recall that Alfred Russel 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 organic evolution here. To do so would lead into the lowermost subtleties 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 development has run much the same course. Three distinctly characterized 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 appears at all.

Then comes the stage of what might be called discursive demonstration. The advance of this beyond the first is enormous in both essentials 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 generalizations 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