We cannot doubt after what we know of the power of heat that the nebulous form of matter was attended by the condition of a very high temperature. - Robert Chambers

Ascending to the next group of rocks, we find the traces of life become more abundant, the number of species extended, and important additions made in certain vestiges of fuci, or sea plants, and of fishes. This group of rocks has been called by English geologists, the Silurian System, because largely developed at the surface of a district of western England, formerly occupied by a people whom the Roman historians call Silures.

The nobler orders of being, including man himself, were contemplated from the first, and came into existence by virtue of a law, the operation of which had commenced ages before their forms were realized.

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.