'It was impossible, I think, for anyone to read my work and not to perceive that my notion of uniformity in the existing causes of change always implied that they must for ever produce an endless variety of effects, _both in the animate and inanimate world_[80].' And to Sedgwick, Lyell wrote:-- 'Now touching my opinion,' concerning the creation of new species at the present day, 'I have no right to object, _as I really entertain it_, to your controverting it; at the same time you will see, on reading my chapter on the subject, that I have studiously avoided laying down the doctrine dogmatically as capable of proof. I have admitted that we have only data for _extinction_, and I have left it to be inferred, instead of enunciating it even as my opinion, that the place of lost species is filled up (as it was of old) from time to time by new species. I have only ventured to say that had new mammalia come in, we could hardly have hoped to verify the fact[81].' That Lyell was convinced of the truth of the doctrine of the evolution of species is shown by his correspondence with friends and sympathisers like Scrope and John Herschel. But he wrote: 'If I had stated ... the possibility of the introduction or origination of fresh species being a natural, in contradistinction to a miraculous process, I should have raised a host of prejudices against me, which are unfortunately opposed at every step to any philosopher who attempts to address the public on these mysterious subjects[82].' That Lyell was justified in not increasing the difficulties which would retard the reception of his views, by introducing matter, which he still regarded as of a more or less speculative character, I think everyone will be prepared to admit. Darwin had to contend with the same difficulty in writing the _Origin of Species_. To have included the question of the origin of mankind _prominently_ in that work would have raised an almost insurmountable barrier to its reception. He says in his autobiography, 'I thought it best, in order that no honourable man should accuse me of concealing my views, to add that by the work "light would be thrown on the origin of man and his history." It would have been useless and injurious to the success of the book to have paraded, without giving evidence, my conviction with respect to his origin[83].' Huxley and Haeckel have both borne testimony to the fact that Lyell, at the time he wrote the _Principles_, was firmly convinced that new species had originated by evolution from old ones. Indeed in a letter to John Herschel in 1836 he goes very far in the direction of anticipating the lines in which enquiries on the _method_ of evolution must proceed, having even a prevision of the doctrine of _mimicry_, long afterwards established by Bates and others. Lyell wrote:--