difficulties had been removed by himself or were likely to be removed within a single generation by the collective work of the whole scientific world. The present generation has witnessed a tendency toward restricting the probable limits of the efficacy of natural selection, followed by an equally marked tendency toward enlarging them—a tendency likely to be furthered by Mr. Wallace's recent book, pointing out the great extent of variation that normally goes on within the limits of one and the same species. Such minor fluctuations in scientific theory occur in all departments of inquiry, but no one doubts the essential soundness of the Darwinian theory, and as for the doctrine of special creations which it superseded, we shall probably go back to it when we go back to stone arrow-heads and the primitive Aryan ox-cart, and not before.
It has more than once been observed that, when a new discovery in science is announced to the world, people at first scout it as ridiculous or frown upon it as impious, but afterward, when it is no longer possible to gainsay it, they suddenly find that everybody knew all about it long ago. This habit is probably due to an exaggerated regard for consistency and a failure to realize that the thoughts of men are, and ought to be, widened with the progress of the suns. About the origin and history of the doctrine of evolution there is in the popular mind a great confusion of ideas; and this, as we now begin to see, is because the conception of evolution is itself something which has grown up gradually. It is an end toward which the whole momentum of scientific thought since Newton's day has been tending, yet which has been clearly and fully recognized only of late years. As regards Mr. Darwin's contribution to the general result, it admits of precise definition. The doctrine of natural selection, which Mr. Spencer afterward called "the survival of the fittest," belongs to Mr. Darwin and to Mr. Wallace as much as the differential calculus belongs to Newton and Leibnitz. The same problem was solved in the same way, first by Mr. Darwin, and then a dozen years later by Mr. Wallace in complete ignorance of what Mr. Darwin had done. "Darwinism" is the doctrine which maintains that many different forms of animal and vegetable life have a common ancestry, and which defines and describes natural selection as the chief agent in bringing about divergencies. Its distinctive feature—that which constitutes its value and its grandeur as a scientific doctrine—is the discovery and demonstration of the agency of natural selection. No one anticipated Mr. Darwin in that.
But the doctrine of natural selection is one thing, and the doctrine of evolution is quite another thing. It covers much more ground, and a good deal of it is ground with which Mr. Darwin had little or nothing to do. Vague notions of evolution were in
