'I have recently read afresh the first edition of the _Principles of Geology_; and when I consider that this remarkable book had been nearly thirty years in everybody's hands, and that it brings home to any reader of ordinary intelligence a great principle and a great fact--the principle, that the past must be explained by the present, unless good cause be shown to the contrary; and the fact, that, so far as our knowledge of the past history of life on our globe goes, no such cause can be shown--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[79].' How strongly Lyell had become convinced, as early as 1832, of the truth and importance of the doctrine of Evolution--in the _organic_ as well as in the inorganic world--in spite of his emphatic rejection of the theory of Lamarck, we shall show in the next chapter. It was this conviction, as we shall see, which led to his friendly encouragement of Darwin in his persevering investigations and to his constant solicitude that the results of his friend's labours should not be lost through delay in their publication. CHAPTER VIII EARLY ATTEMPTS TO ESTABLISH THE DOCTRINE OF EVOLUTION FOR THE ORGANIC WORLD In studying the history of Evolutionary ideas, it is necessary to keep in mind that there are two perfectly distinct lines of thought, the origin and development of which have to be considered. _First._ The conviction that species are not immutable, but that, by some means or other, new forms of life are derived from pre-existing ones. _Secondly._ The conception of some process or processes, by which this change of old forms into new ones may be explained. Buffon, Kant, Goethe, and many other philosophic thinkers, have been more or less firmly persuaded of the truth of the first of these propositions; and even Linnaeus himself was ready to make admissions in this direction. It was impossible for anyone who was convinced of the truth of the doctrine of continuity or evolution in the _inorganic_ world, to avoid the speculation that the same arguments by which the truth of that doctrine was maintained must apply also to the _organic_ world. Hence we find that directly the _Principles of Geology_ was published, thinkers, like Sedgwick and Whewell, at once taxed Lyell with holding that 'the creation of new species is going on at the present day,' and Lyell replied to the latter:--