MODERN GEOLOGY 



Now, however, it has become axiomatic one can hard- 

 ly realize that it was ever doubted. Every new scien- 

 tific truth, says Agassiz, must pass through three stages 

 first, men say it is not true; then they declare it hos- 

 tile to religion ; finally, they assert that every one has 

 known it always. Hutton's truth that natural law is 

 changeless and eternal has reached this final stage. 

 Nowhere now could you find a scientist who would dis- 

 pute the truth of that text which Lyell, quoting from 

 Playfair's Illustrations of the Huttonian Theory, printed 

 on the title-page of his Principles: " Amid all the revo- 

 lutions of the globe the economy of Nature has been 

 uniform, and her laws are the only things that have 

 resisted the general movement. The rivers and the 

 rocks, the seas and the continents, have been changed 

 in all their parts; but the laws which direct those 

 changes, and the rules to which they are subject, have 

 remained invariably the same." 



But, on the other hand, Hutton and Playfair, and in 

 particular Lyell, drew inferences from this principle 

 which the modern physicist can by no means admit. 

 To them it implied that the changes on the surface of 

 the earth have always been the same in degree as well 

 as in kind, and must so continue while present forces 

 hold their sway. In other words, they thought of the 

 world as a great perpetual-motion machine. But the 

 modern physicist, given truer mechanical insight by the 

 doctrines of the conservation and the dissipation of en- 

 ergy, will have none of that. Lord Kelvin, in par- 

 ticular, has urged that in the periods of our earth's in- 

 fancy and adolescence its developmental changes must 

 have been, like those of any other infant organism, 



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