the one depends on the axioms of geometry, the other depends on the axioms of causation. 30. So far then, Geology has no need to regard Astronomy as her superior; and least of all, when they apply themselves together to speculations like these. 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 organization 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 decypher 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. 31. When, therefore, Geology tells us that the earth, which has been the seat of human life for a few thousand years only, has been the seat of animal life for myriads, it may be, millions of years, she has a right to offer this, as an answer to any difficulty which Astronomy, or the readers of astronomical books, may suggest, derived from the considerations that the Earth, the seat of human life, is but one globe of a few thousand miles in diameter, among millions of other globes, at distances millions of times as great. 32. Let the difficulty be put in any way the objector pleases. Is it that it is unworthy of the greatness and majesty of God, according to our conceptions of Him, to bestow such peculiar care on so small a part of His creation? But we know, from geology, that He has bestowed upon this small part of His creation, mankind, this special care;--He has made their period, though only a moment in the ages of animal life, the only period of intelligence, morality, religion. If then, to suppose that He has done this, is contrary to our conceptions of His greatness and majesty, it is plain that our conceptions are erroneous; they have taken a wrong direction. God has not judged, as to what is worthy of Him, as we have judged. He has found it worthy of Him to bestow upon man His special care, though he occupies so small a portion of time; and why not, then, although he occupies so small a portion of space?