CHAPTER IV 

 THE LAW OF EVOLUTION 



LAPLACE has somewhere reminded us 

 that, while gratefully rendering to New- 

 •• ton the homage due to him for his 

 transcendent achievements, we must not forget 

 how singularly fortunate he was in this — that 

 there was but one law of gravitation to be dis- 

 covered. The implication that, if Newton had 

 not lived, Laplace might himself have been the 

 happy discoverer is perhaps a legitimate one, 

 though it does not now especially concern us. 

 But the implied assertion that Nature had no 

 more hidden treasures comparable in worth and 

 beauty to that with which she rewarded the 

 patient sagacity of the great astronomer is one 

 which recent events have most signally refuted. 

 We now know that other laws remained be- 

 hind — as yet others still remain — unrevealed ; 

 laws of nature equalling the law of gravitation 

 in universality, and moreover quite as coy of 

 detection. For while it may be admitted that 

 the demonstrations in the " Principia " required 

 the highest power of quantitative reasoning yet 

 manifested by the human mind ; and while the 

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