'ORIGIN OF SPECIES.' 83 



After my return to England it appeared to me that 

 by following the example of Lyell in Geology, and by 

 collecting all facts which bore in any way on the varia- 

 tion of animals and plants under domestication and 

 nature, some light might perhaps be thrown on the 

 whole subject. My first note-book was opened in July 

 1837. I worked on true Baconian principles, and 

 without any theory collected facts on a wholesale 

 scale, more especially with respect to domesticated 

 productions, by printed enquiries, by conversation 

 with skilful breeders and gardeners, and by extensive 

 reading. When I see the list of books of all kinds 

 which I read and abstracted, including whole series 

 of Journals and Transactions, I am surprised at my 

 industry. I soon perceived that selection was the 

 keystone of man's success in making useful races of 

 animals and plants. But how selection could be ap- 

 plied to organisms living in a state of nature remained 

 for some time a mystery to me. 



In October 1838, that is, fifteen months after I had 

 begun my systematic enquiry, I happened to read for 

 amusement ' Malthus on Population/ and being well 

 prepared to appreciate the struggle for existence 

 which everywhere goes on from long-continued obser- 

 vation of the habits of animals and plants, it at once 

 struck me that under these circumstances favourable 

 variations would tend to be preserved, and unfavour- 

 able ones to be destroyed. The result of this would 

 be the formation of new species. Here then I had at 

 last got a theory by which to work ; but I was so 

 anxious to avoid prejudice, that I determined not for 



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