270 EVOLUTION [Chap. IV 



Letter 190 great force. I think it would be better to do away with all 

 such qualifying expressions, and constantly maintain (what 1 

 certainly believe to be the fact) that variations of every kind 

 are always occurring in every part of every species, and 

 therefore that favourable variations are always ready when 

 wanted. You have, I am sure, abundant materials to prove 

 this ; and it is, I believe, the grand fact that renders modifi- 

 cation and adaptation to conditions almost always possible. 

 I would put the burthen of proof on my opponents to show 

 that any one organ, structure, or faculty does not vary, even 

 during one generation, among all the individuals of a species ; 

 and also to show any mode or way in which any such organ, 

 etc., does not vary. I would ask them to give any reason for 

 supposing that any organ, etc., is ever absolutely identical 

 at any one time in all the individuals of a species, and if not 

 then it is always varying, and there are always materials 

 which, from the simple fact that " the fittest survive," will 

 tend to the modification of the race into harmony with 

 changed conditions. 



I hope these remarks may be intelligible to you, and that 

 you will be so kind as to let me know what you think of 

 them. 



I have not heard for some time how you are getting on. 

 I hope you are still improving in health, and that you will 

 now be able to get on with your great work, for which so 

 many thousands are looking with interest. 



Letter 191 To A. R. Wallace. 1 



Down, July 5th [1866]. 

 I have been much interested by your letter, which is as 

 clear as daylight. I fully agree with all that you say on the 

 advantages of H. Spencer's excellent expression of " the 

 survival of the fittest." This, however, had not occurred to 

 me till reading your letter. It is, however, a great objection 

 to this term that it cannot be used as a substantive governing 

 a verb ; and that this is a real objection I infer from H. 

 Spencer continually using the words Natural Selection. I 

 formerly thought, probably in an exaggerated degree, that it 

 was a great advantage to bring into connection natural and 

 artificial selection ; this indeed led me to use a term in 



1 From Life and Letters, III., p. 45. 



