40 AUTOBIOGRAPHY. [Ch. II. 



following the example of Lyell in Geology, and by collecting 

 all facts which bore in any way on the variation 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 prin- 

 ciples, 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 applied 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 observation of the habits of animals and plants, it at 

 once struck me that under these circumstances favourable 

 variations would tend to be preserved, and unfavourable 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 some time to write even the briefest sketch 

 of it. In June 1842 I first allowed myself the satisfaction of 

 writing a very brief abstract of my theory in pencil in 35 

 pages ; and this was enlarged during the summer of 1844 into 

 one of 230 pages, which I had fairly copied out and still 

 possess. 



But at that time I overlooked one problem of great im- 

 portance ; and it is astonishing to me, except on the principle 

 of Columbus and his egg, how I could have overlooked it and 

 its solution. This problem is the tendency in organic beings 

 descended from the same stock to diverge in character as they 

 become modified. That they have diverged greatly is obvious 

 from the manner in which species of all kinds can be classed 

 under genera, genera under families, families under sub-orders, 

 and so forth ; and I can remember the very spot in the road, 

 whilst in my carriage, when to my joy the solution occurred to 

 me; and this was long after I had come to Down. The 

 solution, as I believe, is that the modified offspring of all 

 dominant and increasing forms tend to become adapted to 

 aaany and highly diversified places in the economy of nature. 



