"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[128] 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[129] 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,[130] 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.'"