The only secondary cause... which has, as yet, been even conjecturally brought forward, to explain how, in the ordinary course of nature, a new speci… - Charles Lyell

Now, when the notion had once gained ground, whether from causes before suggested or not, that the earth had been destroyed by several general catastrophes, it would next be inferred that the human race had been as often destroyed and renovated. And, since every extermination was assumed to be penal, it could only be reconciled with divine justice, by the supposition that man, at each successive creation, was regenerated in a state of purity and innocence.

So long as Geology had not lifted up a part of the veil... it was easy to treat these questions as too transcendental... But it is no longer possible to restrain curiosity from attempting to pry into the relations which connect the present state of the animal and vegetable worlds, as well as of the various races of mankind, with the state of the fauna and flora which immediately preceded.

Of Dr. Hooker, whom I have often cited in this chapter, Mr. Darwin has spoken in the Introduction to his 'Origin of Species, as one 'who had, for fifteen years, aided him in every possible way, by his large stores of knowledge, and his excellent judgement.' This distinguished botanist published his 'Introductory Essay to the Flora of Australia' in 1859, the year after the memoir on 'Natural Selection' was communicated to the Linnaean Society, and a few months before the appearance of the' Origin of Species.' ...no one was better qualified by observation and reflection to give an authoritative opinion on the question, whether the present vegetation of the globe is or is not in accordance with the theory which Mr. Darwin has proposed. We cannot but feel, therefore, deeply interested when we find him making the following declaration: 'The mutual relations of the plants of each great botanical province, and, in fact, of the world generally, is just such as would have resulted if variation had gone on operating throughout indefinite periods, in the same manner as we see it act in a limited number of centuries, so as gradually to give rise in the course of time, to the most widely divergent forms. ...The element of mutability pervades the whole Vegetable Kingdom; no class, nor order, nor genus of more than a few species claims absolute exemption from it, whilst the grand total of unstable forms, generally assumed to be species, probably exceeds that of the stable.'