PROFESSOR HUXLEY'S LECTURES. 55 



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 con- 

 stant 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 knowl- 

 edge 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 sud- 

 den 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 thus by slow degrees one fauna has been replaced by another.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 strati- 

 fied 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 fol- 

 lowed other than their natural and orderly sequence. 



That, I say, is the most natural teaching of the circumstantial evi- 

 dence contained in the stratified rock. I leave you* to consider how 

 far by any ingenuity of interpretation, by any stretching of the mean- 

 ing 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 testi- 

 monial 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 unin- 

 telligible. She is often puzzling, and I have no reason to suppose she 



