Introduction 



Habit," " Evolution, Old and New," "Un- 

 conscious Memory " and " Luck or Cunning." 

 An occasion for the publication of these essays 

 seemed to be afforded by the appearance in 

 1889 of Mr. Alfred Russel Wallace's "Dar- 

 winism " ; and although nearly fourteen years 

 have elapsed since they were published in the 

 Universal Review, I have no fear that they 

 will be found to be out of date. How far, 

 indeed, the problem embodied in the deadlock 

 of which Butler speaks is from solution was 

 conclusively shown by the correspondence 

 which appeared in the Times in May 1903, 

 occasioned by some remarks made at Univer- 

 sity College by Lord Kelvin in moving a 

 vote of thanks to Professor Henslow after his 

 lecture on " Present Day Rationalism." Lord 

 Kelvin's claim for a recognition of the fact 

 that in organic nature scientific thought is 

 compelled to accept the idea of some kind 

 of directive power, and his statement that 

 biologists are coming once more to a firm 

 acceptance of a vital principle, drew from 

 several distinguished men of science retorts 

 heated enough to prove beyond a doubt that 



