throughout the animal and vegetable world, and has to be kept down by sharp preventive checks; so that not more than one of a hundred or a thousand of the individuals whose existence is so wonderfully and so sedulously provided for ever comes to anything, under ordinary circumstances; so the lucky and the strong must prevail, and the weaker and ill-favored must perish; and then follows, as naturally as one sheep follows another, the chapter on “Natural Selection,” Darwin’s cheval de bataille, which is very much the Napoleonic doctrine that Providence favors the strongest battalions—­that, since many more individuals are born than can possibly survive, those individuals and those variations which possess any advantage, however slight, over the rest, are in the long-run sure to survive, to propagate, and to occupy the limited field, to the exclusion or destruction of the weaker brethren.  All this we pondered, and could not much object to.  In fact, we began to contract a liking for a system which at the outset illustrates the advantages of good breeding, and which makes the most “of every creature’s best.”

Could we “let by-gones be by-gones,” and, beginning now, go on improving and diversifying for the future by natural selection, could we even take up the theory at the introduction of the actually existing species, we should be well content; and so, perhaps, would most naturalists be.  It is by no means difficult to believe that varieties are incipient or possible species, when we see what trouble naturalists, especially botanists, have to distinguish between them—­one regarding as a true species what another regards as a variety; when the progress of knowledge continually increases, rather than diminishes, the number of doubtful instances; and when there is less agreement than ever among naturalists as to what is the basis in Nature upon which our idea of species reposes, or how the word is to be defined.  Indeed, when we consider the endless disputes of naturalists and ethnologists over the human races, as to whether they belong to one species or to more, and, if to more, whether to three, or five, or fifty, we can ‘hardly help fancying that both may be right—­or rather, that the uni-humanitarians would have been right many thousand years ago, and the multi-humanitarians will be several thousand years later; while at present the safe thing to say is, that probably there is some truth on both sides.

“Natural selection,” Darwin remarks, “leads to divergence of character; for the more living beings can be supported on the same area, the more they diverge in structure, habits, and constitution” (a principle which, by-the-way, is paralleled and illustrated by the diversification of human labor); and also leads to much extinction of intermediate or unimproved forms.  Now, though this divergence may “steadily tend to increase,” yet this is evidently a slow process in Nature, and liable to much counteraction wherever man does not interpose, and so not likely to work much