In September, 1854, his Cirripede work was practically finished, and he wrote to Sir J. Hooker:
"I have been frittering away my time for the last several weeks in a wearisome manner, partly idleness, and odds and ends, find sending ten thousand Barnacles[123 - The duplicate type-specimens of my father's Cirripedes are in the Liverpool Free Public Museum, as I learn from the Rev. H. H. Higgins.] out of the house all over the world. But I shall now in a day or two begin to look over my old notes on species. What a deal I shall have to discuss with you; I shall have to look sharp that I do not 'progress' into one of the greatest bores in life, to the few like you with lots of knowledge."
CHAPTER IX.
THE FOUNDATIONS OF THE 'ORIGIN OF SPECIES.'
To give an account of the development of the chief work of my father's life – the Origin of Species, it will be necessary to return to an earlier date, and to weave into the story letters and other material, purposely omitted from the chapters dealing with the voyage and with his life at Down.
To be able to estimate the greatness of the work, we must know something of the state of knowledge on the species question at the time when the germs of the Darwinian theory were forming in my father's mind.
For the brief sketch which I can here insert, I am largely indebted to vol. ii. chapter v. of the Life and Letters– a discussion on the Reception of the Origin of Species which Mr. Huxley "was good enough to write for me, also to the masterly obituary essay on my father, which the same writer contributed to the Proceedings of the Royal Society."[124 - Vol. xliv. No. 269.]
Mr. Huxley has well said[125 - Life and Letters, vol. ii. p. 180.]:
"To any one who studies the signs of the times, the emergence of the philosophy of Evolution, in the attitude of claimant to the throne of the world of thought, from the limbo of hated and, as many hoped, forgotten things, is the most portentous event of the nineteenth century."
In the autobiographical chapter, my father has given an account of his share in this great work: the present chapter does little more than expand that story.
Two questions naturally occur to one: (1) – When and how did Darwin become convinced that species are mutable? How (that is to say) did he begin to believe in evolution. And (2) – When and how did he conceive the manner in which species are modified; when did he begin to believe in Natural Selection?
The first question is the more difficult of the two to answer. He has said in the Autobiography (p. 39) that certain facts observed by him in South America seemed to be explicable only on the "supposition that species gradually become modified." He goes on to say that the subject "haunted him"; and I think it is especially worthy of note that this "haunting," – this unsatisfied dwelling on the subject was connected with the desire to explain how species can be modified. It was characteristic of him to feel, as he did, that it was "almost useless" to endeavour to prove the general truth of evolution, unless the cause of change could be discovered. I think that throughout his life the questions 1 and 2 were intimately, – perhaps unduly so, connected in his mind. It will be shown, however, that after the publication of the Origin, when his views were being weighed in the balance of scientific opinion, it was to the acceptance of Evolution not of Natural Selection that he attached importance.
An interesting letter (Feb. 24, 1877) to Dr. Otto Zacharias,[126 - This letter was unaccountably overlooked in preparing the Life and Letters for publication.] gives the same impression as the Autobiography: —
"When I was on board the Beagle I believed in the permanence of species, but as far as I can remember, vague doubts occasionally flitted across my mind. On my return home in the autumn of 1836, I immediately began to prepare my Journal for publication, and then saw how many facts indicated the common descent of species, so that in July, 1837, I opened a note-book to record any facts which might bear on the question. But I did not become convinced that species were mutable until, I think, two or three years had elapsed."
Two years bring us to 1839, at which date the idea of natural selection had already occurred to him – a fact which agrees with what has been said above. How far the idea that evolution is conceivable came to him from earlier writers it is not possible to say. He has recorded in the Autobiography (p. 38) the "silent astonishment with which, about the year 1825, he heard Grant expound the Lamarckian philosophy." He goes on: —
"I had previously read the Zoonomia of my grandfather, in which similar views are maintained, but without producing any effect on me. Nevertheless, it is probable that the hearing rather early in life such views maintained and praised, may have favoured my upholding them under a different form in my Origin of Species. At this time I admired greatly the Zoonomia; but on reading it a second time after an interval of ten or fifteen years, I was much disappointed; the proportion of speculation being so large to the facts given."
Mr. Huxley has well said (Obituary Notice, p. ii.): "Erasmus Darwin, was in fact an anticipator of Lamarck, and not of Charles Darwin; there is no trace in his works of the conception by the addition of which his grandson metamorphosed the theory of evolution as applied to living things, and gave it a new foundation."
On the whole it seems to me that the effect on his mind of the earlier evolutionists was inappreciable, and as far as concerns the history of the Origin of the Species, it is of no particular importance, because, as before said, evolution made no progress in his mind until the cause of modification was conceivable.
I think Mr. Huxley is right in saying[127 - Obituary Notice, p. viii.] that "it is hardly too much to say that Darwin's greatest work is the outcome of the unflinching application to biology of the leading idea, and the method applied in the Principles to Geology." Mr. Huxley has elsewhere[128 - Life and Letters, vol. ii. p. 190. In Mr. Huxley's chapter the passage beginning "Lyell with perfect right…" is given as a footnote: it will be seen that I have incorporated it with Mr. Huxley's text.] admirably expressed the bearing of Lyell's work in this connection: —
"I cannot but believe that Lyell, for others, as for myself, was the chief agent in smoothing the road for Darwin. For consistent uniformitarianism postulates evolution as much in the organic as in the inorganic world. The origin of a new species by other than ordinary agencies would be a vastly greater 'catastrophe' than any of those which Lyell successfully eliminated from sober geological speculation…
"Lyell,[129 - Lyell's Life and Letters, Letter to Haeckel, vol. ii. p. 436. Nov. 23, 1868.] with perfect right, claims this position for himself. He speaks of having 'advocated a law of continuity even in the organic world, so far as possible without adopting Lamarck's theory of transmutation…
"'But while I taught,' Lyell goes on, 'that as often as certain forms of animals and plants disappeared, for reasons quite intelligible to us, others took their place by virtue of a causation which was beyond our comprehension; it remained for Darwin to accumulate proof that there is no break between the incoming and the outgoing species, that they are the work of evolution, and not of special creation… I had certainly prepared the way in this country, in six editions of my work before the Vestiges of Creation appeared in 1842 [1844], for the reception of Darwin's gradual and insensible evolution of species.'"
Mr. Huxley continues: —
"If one reads any of the earlier editions of the Principles carefully (especially by the light of the interesting series of letters recently published by Sir Charles Lyell's biographer), it is easy to see that, with all his energetic opposition to Lamarck, on the one hand, and to the ideal quasi-progressionism of Agassiz, on the other, Lyell, in his own mind, was strongly disposed to account for the origination of all past and present species of living things by natural causes. But he would have liked, at the same time, to keep the name of creation for a natural process which he imagined to be incomprehensible."
The passage above given refers to the influence of Lyell in preparing men's minds for belief in the Origin, but I cannot doubt that it "smoothed the way" for the author of that work in his early searchings, as well as for his followers. My father spoke prophetically when he wrote the dedication to Lyell of the second edition of the Journal of Researches (1845).
"To Charles Lyell, Esq., F.R.S., this second edition is dedicated with grateful pleasure – as an acknowledgment that the chief part of whatever scientific merit this journal and the other works of the author may possess, has been derived from studying the well-known and admirable Principles of Geology."
Professor Judd, in some reminiscences of my father which he was so good as to give me, quotes him as saying that, "It was the reading of the Principles of Geology which did most towards moulding his mind and causing him to take up the line of investigation to which his life was devoted."
The rôle that Lyell played as a pioneer makes his own point of view as to evolution all the more remarkable. As the late H. C. Watson wrote to my father (December 21, 1859): —
Now these novel views are brought fairly before the scientific public, it seems truly remarkable how so many of them could have failed to see their right road sooner. How could Sir C. Lyell, for instance, for thirty years read, write, and think, on the subject of species and their succession, and yet constantly look down the wrong road!
"A quarter of a century ago, you and I must have been in something like the same state of mind on the main question. But you were able to see and work out the quo modo of the succession, the all-important thing, while I failed to grasp it."
In his earlier attitude towards evolution, my father was on a par with his contemporaries. He wrote in the Autobiography: —
"I occasionally sounded not a few naturalists, and never happened to come across a single one who seemed to doubt about the permanence of species: " and it will be made abundantly clear by his letters that in supporting the opposite view he felt himself a terrible heretic.
Mr. Huxley[130 - Life and Letters, vol. ii. p. 188.] writes in the same sense: —
"Within the ranks of biologists, at that time [1851-58], I met with nobody, except Dr. Grant, of University College, who had a word to say for Evolution – and his advocacy was not calculated to advance the cause. Outside these ranks, the only person known to me whose knowledge and capacity compelled respect, and who was, at the same time, a thorough-going evolutionist, was Mr. Herbert Spencer, whose acquaintance I made, I think, in 1852, and then entered into the bonds of a friendship which, I am happy to think, has known no interruption. Many and prolonged were the battles we fought on this topic. But even my friend's rare dialectic skill and copiousness of apt illustration could not drive me from my agnostic position. I took my stand upon two grounds: firstly, that up to that time, the evidence in favour of transmutation was wholly insufficient; and, secondly, that no suggestion respecting the causes of the transmutation assumed, which had been made, was in any way adequate to explain the phenomena. Looking back at the state of knowledge at that time, I really do not see that any other conclusion was justifiable."
These two last citations refer of course to a period much later than the time, 1836-37, at which the Darwinian theory was growing in my father's mind. The same thing is however true of earlier days.
So much for the general problem: the further question as to the growth of Darwin's theory of natural selection is a less complex one, and I need add but little to the history given in the Autobiography of how he came by that great conception by the help of which he was able to revivify "the oldest of all philosophies – that of evolution."
The first point in the slow journey towards the Origin of Species was the opening of that note-book of 1837 of which mention has been already made. The reader who is curious on the subject will find a series of citations from this most interesting note-book, in the Life and Letters, vol. ii. p. 5, et seq.
The two following extracts show that he applied the theory of evolution to the "whole organic kingdom" from plants to man.
"If we choose to let conjecture run wild, then animals, our fellow brethren in pain, disease, death, suffering and famine – our slaves in the most laborious works, our companions in our amusements – they may partake [of] our origin in one common ancestor – we may be all melted together."
"The different intellects of man and animals not so great as between living things without thought (plants), and living things with thought (animals)."
Speaking of intermediate forms, he remarks: —
"Opponents will say —show them me. I will answer yes, if you will show me every step between bulldog and greyhound."
Here we see that the argument from domestic animals was already present in his mind as bearing on the production of natural species, an argument which he afterwards used with such signal force in the Origin.
A comparison of the two editions of the Naturalists' Voyage is instructive, as giving some idea of the development of his views on evolution. It does not give us a true index of the mass of conjecture which was taking shape in his mind, but it shows us that he felt sure enough of the truth of his belief to allow a stronger tinge of evolution to appear in the second edition. He has mentioned in the Autobiography (p. 40), that it was not until he read Malthus that he got a clear view of the potency of natural selection. This was in 1838 – a year after he finished the first edition (it was not published until 1839), and seven years before the second edition was issued (1845). Thus the turning-point in the formation of his theory took place between the writing of the two editions. Yet the difference between the two editions is not very marked; it is another proof of the author's caution and self-restraint in the treatment of his ideas. After reading the second edition of the Voyage we remember with a strong feeling of surprise how far advanced were his views when he wrote it.
These views are given in the manuscript volume of 1844, mentioned in the Autobiography. I give from my father's Pocket-book the entries referring to the preliminary sketch of this historic essay.
"1842, May 18, – Went to Maer. June 15– to Shrewsbury, and 18th to Capel Curig. During my stay at Maer and Shrewsbury … wrote pencil sketch of species theory."[131 - I have discussed in the Life and Letters the statement often made that the first sketch of his theory was written in 1839.]
In 1844, the pencil-sketch was enlarged to one of 230 folio pages, which is a wonderfully complete presentation of the arguments familiar to us in the Origin.
The following letter shows in a striking manner the value my father put on this piece of work.
C. D. to Mrs. Darwin. Down [July 5, 1844]
… I have just finished my sketch of my species theory. If, as I believe, my theory in time be accepted even by one competent judge, it will be a considerable step in science.