Alfred Russel Wallace 



with the numerous problems to which they give rise. 

 Thenceforward 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 minds were freshly stored with a considerable 

 body of personal observation and reflection bearing upon 

 the problem to be solved, had our attention directed to 

 the system of positive checks as expounded by Malthus in 

 his ** Principles of Population. '^ The effect of that was 

 analogous to that of friction upon the specially prepared 

 match, producing that flash of insight which led us imme- 

 diately to the simple but universal law of the '* survival 

 of the fittest,'' as the long- sought effective cause of the 

 continuous modification and adaptations of living things. 



It is an unimportant detail that Darwin read this book 

 two years after his return from his voyage, while I read it 

 lefore 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 external 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 Kobert 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 and Prichard 

 — possess any adequate knowledge of the class of facts 

 above referred to, or sufficient antecedent interest in the 



116 



