2 Darwinism and Other Essays. 



apprehended, the opposition to the Newtonian 

 theory was not silenced till 1759, when Clairaut 

 and Lalande, by calculating the retardation of 

 Halley's comet, furnished such crucial proof as 

 could not possibly be overcome. At this time 

 Newton had been thirty -two years in his grave ; 

 seventy-two years had elapsed since the publi- 

 cation of the " Principia," and ninety-four since 

 the hypothesis was first definitely conceived. 



In the present age, when the number of sci- 

 entific inquirers has greatly increased and the in- 

 terchange of thoughts^has become rapid and con- 

 stant, it takes much less time for a new gener- 

 alization to make its way into people's minds. 

 It is now barely eighteen years since Mr. Dar- 

 win's views on the origin of species were an- 

 nounced in a book which purported to be only 

 the rough preliminary sketch of a greater work 

 in course of preparation. But, though greeted at 

 the beginning with ridicule and opprobrium, the 

 theory of natural selection has already won a 

 complete and overwhelming victory. One could 

 count on one's fingers the number of eminent 

 naturalists who still decline to adopt it, and the 

 hesitancy of these appears to be determined in 

 the main by theological or metaphysical, and 

 therefore not strictly relevant, objections. But 



