II
Darwin first began to be interested in the idea of modification by descent during his voyage on the Beagle and in the year 1837.[400] In his earlier years he had been satisfied with the conventionally orthodox theological and scientific conception of the creation of distinct species, and all his youthful work had been on the basis of this view. Such phrases as the note, written in 1834, in Valparaiso: ‘It seems not a very improbable conjecture that the want of animals may be owing to none having been created since this country was raised from the sea,’[401] are obviously significant of the earlier attitude. But as he observed more widely and became more and more impressed with the infinite diversity of forms and the delicacy of shading with which they pass into each other, the conviction grew that the possibilities of development were unlimited, and that individual differences might pass into varieties and these again into species, making the origin of varied life far simpler and more unified than had ever been imagined. And such an evolutionary process seemed much more in accord with general natural laws than the abrupt appearance of fixed, highly organized forms in sudden sufficiency. As he says, ‘the subject haunted me,’ and from a very early period he began making notes and memoranda of all observations that might bear for—or against—the gradual modification of species.
A PAGE FROM A NOTEBOOK OF 1837
The difficulty was to imagine just how the process of modification was brought about, and until he could get some light on this point, his enthusiasm for the general idea was chilled and baffled. As we have seen, Lamarck’s view, that living beings directly adapted themselves to their surroundings and then transmitted these adaptations to their descendants, seemed at least inadequate, and Darwin felt that the theory must have some more solid basis, if it was to prevail at all. He set his mind to work for months and months, and he applied the intellectual method which he himself has so admirably defined in a letter to his young son: ‘I have been speculating last night what makes a man a discoverer of undiscovered things; and a most perplexing problem it is. Many men who are very clever—much cleverer than the discoverers—never originate anything. As far as I can conjecture, the art consists in habitually searching for the causes and meaning of everything which occurs.’[402]
Searching for the cause and meaning of everything which occurred, he at last achieved the discovery he was looking for, and so knew what is assuredly one of the greatest of spiritual delights. Largely by watching and studying the results of deliberate human selection with plants and animals, he was led to his great principle of natural selection, that is, assuming the tendency in all living beings to vary individually, that in the intense struggle for existence those variations which are beneficial and help the organism to live and prosper will be preserved and transmitted. The causes of variation, whether spontaneous or to be found in environment, Darwin never pretended entirely to explain. Of the principle of natural selection, or as Spencer phrased it in a form which Darwin admitted to be in some respects more satisfactory, ‘the survival of the fittest,’ perhaps its discoverer has given no better statement than the sentences in the second volume of the great work on ‘Plants and Animals under Domestication’: ‘To consider the subject under this point of view is enough to strike one dumb with amazement. But our amazement ought to be lessened when we reflect that beings almost infinite in number, during an almost infinite lapse of time, have often had their whole organization rendered in some degree plastic, and that each slight modification of structure which was in any way beneficial under excessively complex conditions of life has been preserved, whilst each which was in any way injurious has been rigorously destroyed. And the long-continued accumulation of beneficial variations will infallibly have led to structures as diversified, as beautifully adapted for various purposes, and as excellently coördinated, as we see in the animals around us. Hence I have spoken of selection as the paramount power, whether applied by man to the formation of domestic breeds, or by nature to the production of species.’[403]
It is not to be supposed that the first grasp of evolution through variation and natural selection could have carried with it the full foresight of the enormous changes, mental, moral, and spiritual, that such a theory was likely to produce. Still, a mind so keen and active as Darwin’s was bound to catch some suggestion of those changes. For instance, the astonishing and deadly ease with which the old workings of Providential adaptation and design slipped under the new light into mere operations of mechanical law could not fail to foreshadow the philosophical and theological upheaval that was sure to follow. A spirit trained in the conventional atmosphere of the early English nineteenth century must necessarily have regarded such an upheaval with a certain amount of question, awe, and even dismay; and Darwin indisputably had something of these feelings mingled with the triumphant joy of discovery.
It is profoundly characteristic of the man that he did not hasten to fling the discovery to the world, to get the immediate excitement and glory, leaving discussion and substantiation to come afterwards. He was so hesitant, so doubtful of his own methods and his own powers, that he delayed even to commit his conjectures to writing in his note-books, lest they should become hardened and distorted by the prejudice of statement and so misleading. His one idea was to get confirmation, by every line of study and experiment, and for twenty years he toiled with deliberate patience before he was willing to make the attempt to put his results into publishable shape.
And all the time there was the chance, perfectly present to his mind, that death might prevent him from ever making the discovery known. And all the time there was the chance that in the world of scientific thought that was seething about him some one else might anticipate him and propagate the idea, perhaps in a form less convincing and less substantial than he would be able to give it. Just as he was getting to the stage of preparation which he had aimed at, exactly this thing seemed likely to happen. In June 1858, Alfred Russel Wallace, a scientist of standing and ability, with whom Darwin had corresponded, sent him a paper largely anticipating Darwin’s ideas on natural selection, so largely that Darwin wrote of it to Lyell: ‘I never saw a more striking coincidence; if Wallace had my MS. sketch written out in 1842, he could not have made a better short abstract; ... so all my originality, whatever it may amount to, will be smashed.’[404] And he even doubted whether he should make his views public at all, for fear of depriving Wallace of credit: ‘I would far rather burn my whole book, than that he or any other man should think that I had behaved in a paltry spirit.’[405] The difficulty was adjusted, however, by friends, and a joint paper by Darwin and Wallace both, was read at the meeting of the Linnæan Society on July 1, 1858, giving the world the first inkling of what natural selection was to mean. Sir Joseph Hooker wrote prophetically of this meeting: ‘The interest excited was intense, but the subject was too novel and too ominous for the old school to enter the lists, before armoring. After the meeting it was talked over with bated breath.’[406]
The relation between Darwin and Wallace in regard to priority of discovery is one of the finest things in the whole history of science. There was no jealousy, no bitterness, no acrimony, but instead a full recognition of each others’ achievements, and a sympathetic understanding which ripened into a helpful and unbroken friendship. Wallace’s statement of the matter long after Darwin’s death, is as noble in its unselfishness as words can make it: ‘But what is often forgotten by the press and the public is that the idea occurred to Darwin in 1838 ... nearly twenty years earlier than to myself, and that during the whole twenty years he had been laboring collecting evidence from the vast mass of literature of biology, of horticulture, and of agriculture.... Such being the facts of the case, I should have had no cause for complaint if the respective shares of Darwin and myself ... had been henceforth estimated as being roughly proportioned to the time we had each bestowed upon it ... that is to say, as twenty years to one week.’[407] Darwin’s summary, more general, is equally worthy of both: ‘I hope it is a satisfaction to you to reflect—and very few things in my life have been more satisfactory to me—that we have never felt any jealousy towards each other, though in one sense rivals. I believe that I can say this of myself with truth, and I am absolutely sure that it is true of you.’[408]
The first promulgation of the Darwinian ideas, with those of Wallace, was therefore made in July, 1858. In the following year, November, 1859, ‘The Origin of Species’ was published. Darwin himself regarded this book as a mere preliminary sketch, requiring to be supported and buttressed by confirmatory evidence of all sorts. But it at once overwhelmed the world, and has always been looked upon since as the cardinal statement of the theory. As Huxley said of it, ‘It is doubtful if any single book, except the “Principia,” ever worked so great and so rapid a revolution in science, or made so deep an impression on the general mind.’[409] And innumerable quotations could be drawn from other sources to the same effect.