“As to the vastness of astronomical discoveries, we must observe that those of Geology are no less vast: they extend through time, as those of Astronomy do through space; they carry us through millions of years—that is, of the earth’s revolutions—as those of Astronomy through millions of the earth’s diameters, or of diameters of the earth’s orbit. Geology fills the regions of duration with events, as Astronomy the regions of the universe with objects. She carries us backwards by the relation of cause and effect, as Astronomy carries us upwards by the relations of geometry. As Astronomy steps on from point to point of the universe by a chain of triangles, so Geology steps from epoch to epoch of the earth’s history by a chain of mechanical and organical laws. If the one depends on the axioms of geometry, the other depends on the axioms of causation.... But in truth, in such speculations, Geology has an immeasurable superiority. She has the command of an implement, in addition to all that Astronomy can use; and one, for the purpose of such speculations, adapted far beyond any astronomical element of discovery. She has, for one of her studies,—one of her means of dealing with her problems,—the knowledge of life, animal and vegetable. Vital organisation is a subject of attention which has, in modern times, been forced upon her. It is now one of the main parts of her discipline. The geologist must study the traces of life in every form—must learn to decipher its faintest indications and its fullest development. On the question, then, whether there be, in this or that quarter, evidence of life, he can speak with the confidence derived from familiar knowledge; while the astronomer, to whom such studies are utterly foreign, because he has no facts which bear upon them, can offer, on such questions, only the loosest and most arbitrary conjectures, which, as we have had to remark, have been rebuked by eminent men as being altogether inconsistent with the acknowledged maxims of his science.”[13] Before we proceed to state the singular and suggestive argument derived from this splendid science,[14] we may apprise the reader that Dr Whewell’s primary object is to show, that even “supposing the other bodies of the universe to resemble the earth, so far as to seem, by their materials, forms, and motions, no less fitted than she is to be the abodes of life, yet that, knowing what we know of Man, we can believe the earth to be tenanted by a race who are the _special_ objects of God’s care.”[15] The grounds for entertaining, or rather impugning, that supposition he subsequently deals with after his own fashion in Chapters VII., VIII., IX., X.; but the two with which we are at present concerned are the fifth and sixth, respectively entitled, as we intimated in our last Number, “Geology,” and “The Argument from Geology.”