But while Darwin was thus engaged in arranging and classifying the animals and plants he had brought home with him, the germs of those inquiring ideas about the origin of species which we have already observed in his account of the voyage were quickening into fresh life within him. As he ruminated at his leisure over the results of his accumulations, he was beginning to work upon the great problem with the definite and conscious resolution of solving it. 'On my return home, it occurred to me,' he says, 'in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work, I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions that then seemed to me probable; from that period to the present day [1859] I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision.'
So Darwin wrote at fifty. The words are weighty and well worthy of consideration. They give us in a nutshell the true secret of Darwin's success in compelling the attention and assent of his contemporaries to his completed theory. For speculations and hypotheses like those of Lamarck and Erasmus Darwin, however brilliant and luminous they may be, the hard, dry, scientific mind cares as a rule less than nothing. Men of genius and insight like Goethe and Oken may, indeed, seize greedily upon the pregnant suggestion; their intellects are already attuned by nature to its due reception and assimilation; but the mere butterfly-catchers and plant-hunters of the world, with whom after all rests ultimately the practical acceptance or rejection of such a theory, can only be convinced by long and patient accumulations of facts, by infinite instances and endless examples, by exhaustive surveys of the whole field of nature in a thousand petty details piecemeal. They have to be driven by repeated beating into the right path. Everywhere they fancy they see the loophole of an objection, which must be carefully closed beforehand against them with anticipatory argument, as we close hedges by the wayside against the obtrusive donkey with a cautious bunch of thorny brambles. Even if Charles Darwin had hit upon the fundamental idea of natural selection, and had published it, as Wallace did, in the form of a mere splendid _aperçu_, he would never have revolutionised the world of biology. When the great discovery was actually promulgated, it was easy enough to win the assent of philosophical thinkers like Herbert Spencer; easy enough, even, to gain the ready adhesion of non-biological but kindred minds, like Leslie Stephen's and John Morley's; those might all, perhaps, have been readily convinced by far less heavy and crushing artillery than that so triumphantly marshalled together in the 'Origin of Species.' But in order to command the slow and grudging adhesion of the rank and file of scientific workers, the 'hodmen of science,' as Professor Huxley calls them, it was needful to bring together an imposing array of closely serried facts, to secure every post in the rear before taking a single step onward, and to bring to bear upon every antagonist the exact form of argument with which he was already thoroughly familiar. It was by carefully pursuing these safe and cautious philosophical tactics that Charles Darwin gained his great victory. Where others were pregnant, he was cogent. He met the Dryasdusts of science on their own ground, and he put them fairly to flight with their own weapons. More than that, he brought them all over in the long run as deserters into his own camp, and converted them from doubtful and suspicious foes into warm adherents of the evolutionary banner.