As I write these lines (July 1886) I see a paragraph in Nature which I take it is intended to convey the impression that Mr. Francis Darwin’s life and letters of his father will appear shortly.  I can form no idea whether Mr. F. Darwin’s forthcoming work is likely to appear before this present volume; still less can I conjecture what it may or may not contain; but I can give the reader a criterion by which to test the good faith with which it is written.  If Mr. F. Darwin puts the distinctive feature that differentiates Mr. C. Darwin from his predecessors clearly before his readers, enabling them to seize and carry it away with them once for all—­if he shows no desire to shirk this question, but, on the contrary, faces it and throws light upon it, then we shall know that his work is sincere, whatever its shortcomings may be in other respects; and when people are doing their best to help us and make us understand all that they understand themselves, a great deal may be forgiven them.  If, on the other hand, we find much talk about the wonderful light which Mr. Charles Darwin threw on evolution by his theory of natural selection, without any adequate attempt to make us understand the difference between the natural selection, say, of Mr. Patrick Matthew, and that of his more famous successor, then we may know that we are being trifled with; and that an attempt is being again made to throw dust in our eyes.

CHAPTER XVI—­Mr. Grant Allen’s “Charles Darwin”

It is here that Mr. Grant Allen’s book fails.  It is impossible to believe it written in good faith, with no end in view, save to make something easy which might otherwise be found difficult; on the contrary, it leaves the impression of having been written with a desire to hinder us, as far as possible, from understanding things that Mr. Allen himself understood perfectly well.

After saying that “in the public mind Mr. Darwin is perhaps most commonly regarded as the discoverer and founder of the evolution hypothesis,” he continues that “the grand idea which he did really originate was not the idea of ‘descent with modification,’ but the idea of ‘natural selection,’” and adds that it was Mr. Darwin’s “peculiar glory” to have shown the “nature of the machinery” by which all the variety of animal and vegetable life might have been produced by slow modifications in one or more original types.  “The theory of evolution,” says Mr. Allen, “already existed in a more or less shadowy and undeveloped shape;” it was Mr. Darwin’s “task in life to raise this theory from the rank of a mere plausible and happy guess to the rank of a highly elaborate and almost universally accepted biological system” (pp. 3-5).