Why Darwin succeeded 87 
such views had been promulgated ; and many must, as Huxley says, 
have taken up his own position of “critical expectancy1.” 
Why, then, was it, that Darwin succeeded where the rest had 
failed? The cause of that success was two-fold. First,and obviously, 
in the principle of Natural Selection he had a suggestion which would 
work. It might not go the whole way, but it was true as far as it 
went. Evolution could thus in great measure be fairly represented as 
a consequence of demonstrable processes. Darwin seldom endangers 
the mechanism he devised by putting on it strains much greater than 
it can bear. He at least was under no illusion as to the omnipotence 
of Selection ; and he introduces none of the forced pleading which in 
recent years has threatened to discredit that principle. 
For example, in the latest text of the Origin? we find him saying: 
“But as my conclusions have lately been much misrepresented, 
and it has been stated that I attribute the modification of species 
exclusively to natural selection, I may be permitted to remark 
that in the first edition of this work, and subsequently, I placed 
in a most conspicuous position—namely, at the close of the 
Introduction—the following words: ‘I am convinced that natural 
selection has been the main but not the exclusive means of 
modification.’ ” 
1 See the chapter contributed to the Life and Letters of Charles Darwin, u.p.195. I do 
not clearly understand the sense in which Darwin wrote (Autobiography, ibid. 1. p. 87): 
“Tt has sometimes been said that the success of the Origin proved ‘that the subject was in 
the air,’ or ‘that men’s minds were prepared for it.’ I do not think that this is strictly 
true, for 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.” This experience may 
perhaps have been an accident due to Darwin’s isolation. The literature of the period 
abounds with indications of ‘‘critical expectancy.” A most interesting expression of that 
feeling is given in the charming account of the ‘‘Harly Days of Darwinism’’ by Alfred 
Newton, Macmillan’s Magazine, tvt1. 1888, p. 241. He tells how in 1858 when spending a 
dreary summer in Iceland, he and his friend, the ornithologist John Wolley, in default of 
active occupation, spent their days in discussion. ‘‘ Both of us taking a keen interest in 
Natural History, it was but reasonable that a question, which in those days was always 
coming up wherever two or more naturalists were gathered together, should be continually 
recurring. That question was, ‘What is « species?’ and connected therewith was the 
other question, ‘How did a species begin ?’...Now we were of course fairly well acquainted 
with what had been published on these subjects.” He then enumerates some of these 
publications, mentioning among others T. Vernon Wollaston’s Variation of Species— 
a work which has in my opinion never been adequately appreciated. He proceeds: ‘Of 
course we never arrived at anything like a solution of these problems, general or special, 
but we felt very strongly that a solution ought to be found, and that quickly, if the study 
of Botany and Zoology was to make any great advance.” He then describes how on 
his return home he received the famous number of the Linnean Journal on a certain 
evening. ‘‘I sat up late that night to read it; and never shall I forget the impression it 
made upon me. Herein was contained a perfectly simple solution of all the difficulties 
which had been troubling me for months past....1 went to bed satisfied that a solution 
had been found.” 
2 Origin, 6th edit. (1882), p. 421. 
