There is nothing at all singular or special in the astronomical situation of the earth. It takes its place third in a series of planets, which series… - Robert Chambers

I believe my doctrines to be in the main true; I believe all truth to be valuable, and its dissemination a blessing.

Meteoric stones have proved to be a verity, and not an impossibility. About the same time, the fact of so many Gloucestershire peasantry having attested the prevention of small-pox by a virus from the teats of a cow, would have been deemed a sufficient answer to the same pleading, by nine out of every ten of the best educated physicians in England. Jenner's statue in Trafalgar Square tells us how fallacious the objection would have been. It is to be observed regarding such objections, that they are almost invariably gratuitous and unproved. Were they always put to the test of experiment, how many might prove like meteorites and vaccination?

I suggest, then... that the first step was an advance under favor of peculiar conditions, from the simplest forms of being, to the next more complicated, and this through the medium of the ordinary process of generation.