Stress has mainly been laid, in this brief and necessarily imperfect abstract, on the essentially Darwinian principle of natural selection. But Darwin did not himself attribute everything to this potent factor in the moulding of species. 'I am convinced,' he wrote pointedly in the introduction to his first edition, 'that natural selection has been the main but not the exclusive means of modification.' He attributed considerable importance as well to the Lamarckian principle of use and disuse, already so fully insisted upon before him by Mr. Herbert Spencer. The chief factors in his compound theory, as given in his own words at the end of his work, areas follows: 'Growth with Reproduction; Inheritance, which is almost implied by reproduction; Variability, from the indirect and direct action of the conditions of life, and from use and disuse; a Ratio of Increase, so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character, and the Extinction of the less improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows.'
Such was the simple and inoffensive-looking bombshell which Darwin launched from his quiet home at Down into the very midst of the teleological camp in the peaceful year 1859. Subsequent generations will remember the date as a crisis and turning-point in the history of mankind.
[2] The remainder of the present chapter, which consists almost entirely of an exposition of the doctrine of natural selection, may safely be skipped by the reader already well acquainted with the Origin of Species. The abstract is taken for the most part from the latest and fullest enlarged edition, but attention is usually called in passing to the points which did not appear in the first issue of 1859.
[3] The researches of Seebohm and others have since proved that this is really the case to a far greater extent than Darwin was aware of in 1859, or, indeed, till many years afterward.
So far as the scientific world was concerned the 'Origin of Species' fell, like a grain of mustard seed, upon good and well-prepared ground; the plant that sprang from it grew up forthwith into a great and stately tree, that overshadowed with its spreading branches all the corners of the earth.