ORIGIN OF THEORY OF NATURAL SELECTION 399 



when, as in the case of Darwin and myself, the collectors were of a 

 speculative tiii-n of mind, they were constantly led to think upon the 

 " why " and the " how " of all this wonderful variety in nature — thi^ 

 overwhelming, and, at first sight, purposeless wealth of specific forms 

 among the very humblest forms of life. 



Then, a little later (and with both of us almost accidentally) we 

 became travellers, collectors and observers, in some of the richest and 

 most interesting portions of the earth; and we thus had forced upon 

 our attention all the strange phenomena of local and geographical dis- 

 tribution, with the numerous problems to which they give rise. Thence- 

 forward our interest in the great mystery of how species came into 

 existence was intensified, and — again to use Darwin's expression — 

 " haunted " us. 



Finally, both Darwin and myself, at the critical period when our 

 ininds were freshly stored with a considerable body of personal observa- 

 tion and reflection bearing upon the problem to be solved, had our 

 attention directed to the system of positive cliecTfs as expounded by 

 Malthus in his " Principles of Population." The effect of this was 

 analogous to that of friction upon the specially-prepared match, pro- 

 ducing that flash of insight which led us immediately to the simple 

 but universal law of the " survival of the fittest," as the long-sought 

 effective cause of the continuous modification and adaptation of living 

 things. 



It is an unimportant detail that Darwin read this book two years 

 after his return from his voyage, while I had read it hefore I went 

 abroad, and it was a sudden recollection of its teachings that caused 

 the solution to flash upon me. I attach much importance, however, to 

 the large amount of solitude we both enjoyed during our travels, which, 

 at the most impressionable period of our lives, gave us ample time for 

 reflection on the phenomena we were daily observing. 



This view, of the combination of certain mental faculties and ex 

 ternal conditions that led Darwin and myself to an identical conception, 

 also serves to explain why none of our precursors or contemporaries 

 hit upon what is really so very simple a solution of the great problem. 

 Such evolutionists as Robert Chambers, Herbert Spencer and Huxley, 

 though of great intellect, wide knowledge, and immense power of work, 

 had none of them the special turn of mind that makes the collector 

 and the species-man, while they all — as well as the equally great thinker 

 on similar lines, Sir Charles Lyell — became in early life immersed in 

 different lines of research which engaged their chief attention. 



Neither did the actual precursors of Darwin in the statement of the 

 principle — Wells, Matthews or Prichard — possess any adequate knowl- 

 edge of the class of facts above referred to, or suflScient antecedent 

 interest in the problem itself, which were both needed in order to per- 



