xxviii] FRIENDS AND ACQUAINTANCES 85 



'spontaneous variability' into 'unknown causes,' and then, 

 of course, make nonsense of Mr. Darwin's words. In this 

 way I will undertake to make nonsense of any argument. 

 ' Spontaneous variability ' is a FACT, as explained, for 

 example, in my review of Mr. Murphy's book (along with 

 yours) in Nature. It is an absolutely universal fact in the 

 organic world (and for all I know in the inorganic too), and 

 is probably a fundamental fact, due to the impossibility of any 

 two organisms ever having been subjected to exactly identical 

 conditions, and the extreme complexity both of organisms 

 and their environment. This normal variability wants no 

 other explanation. Its absence is inconceivable, because it 

 would imply that diversity of conditions produced identity of 

 result. The wishes or actions of individuals may be one of 

 the causes of variability, but only one out of myriads. Now 

 to say that such an universal fact as this cannot be taken as 

 a basis of reasoning because the exact causes of it are 

 unknown in each ease, is utterly illogical. The causes of 

 gravitation, of electricity, of heat, of all the forces of nature 

 are unknown. Can we not, then, reason on them, and explain 

 other phenomena by them, without having the words 'un- 

 known causes ' substituted, and thus making nonsense ? 



" I am no blind admirer of Mr. Darwin, as my works 

 show ; but I must say your criticism of him in your present 

 work completely fails to reach him. 



" The mere fact that Lamarck's views, though well put 

 before the world for many years by Sir Charles Lyell (and 

 other writers) converted no one, while Darwin has converted 

 almost all the best naturalists in Europe, is a pretty good 

 proof that the one theory is more complete than the other. 

 " Yours very faithfully, 



"Alfred R. Wallace." 



In Nature (June 12) I reviewed this book more fully, 

 showing by numerous quotations how completely Mr. 

 Butler has failed to grasp the essential features of natural 

 selection, while a large portion of his criticism of Mr. 

 Darwin's work is purely verbal and altogether erroneous 



