Page:Popular Science Monthly Volume 10.djvu/65

From Wikisource
Jump to navigation Jump to search
This page has been validated.

sible character, and is simply this: We find raised up on the flanks of these mountains, elevated by the forces of upheaval which have given rise to them, masses of cretaceous rock which formed the bottom of the sea before those mountains existed. It is therefore perfectly clear that the elementary forces which gave rise to the mountains operated subsequently to the Cretaceous epoch; that the mountains themselves are largely made up of the materials deposited in the sea which once occupied their place. We meet as we go back in time with constant alternations of sea and land, of estuary and open ocean, and in correspondence with these alternations we meet with changes in the fauna and flora of the kind I have stated.

But no inspection of these changes gives us the slightest right to believe that there has been any discontinuity in natural processes. There is no trace of cataclysm, of great sweeping deluges or universal destructions of organic life. The appearances which were formerly interpreted that way have all been shown to be delusive as our knowledge has increased and as the blanks between the different formations have been filled up. It can now be shown that there is no absolute break between formation and formation, that there has been no sudden disappearance of all the forms of life at one time and replacement by another, but that everything has gone on slowly and gradually, that one form has died out and another has taken its place, and that thus by slow degrees one fauna has been replaced by another. So that, within the whole of the immense period indicated by these stratified rocks, there is assuredly—leaving evolution out of the question altogether—not the slightest trace of any break in the uniformity of Nature's operations, not a shadow of indication that events have followed other than their natural and orderly sequence.

That, I say, is the most natural teaching of the circumstantial evidence contained in the stratified rock. I leave you* to consider how far by any ingenuity of interpretation, by any stretching of the meaning of language, it can be brought into the smallest similarity with that view which I have put before you as the Miltonic doctrine.

There remains the third hypothesis—what I have spoken of as the hypothesis of evolution; and I propose that in lectures to come we should consider that as carefully as we have considered the other two hypotheses. I need not say that it is quite hopeless to look for testimonial evidence of evolution. The very nature of the case precludes the possibility of such evidence. Our sole inquiry is, what foundation circumstantial evidence lends to that hypothesis, or whether it lends any, or whether it controverts it; and I should deal with the matter entirely as a question of history. I shall not indulge in the discussion of any speculative probabilities. I shall not attempt to show that Nature is unintelligible unless we adopt some such hypothesis: for anything I know about it, it may be the way of Nature to be unintelligible. She is often puzzling, and I have no reason to suppose she