y," as printed in Volume 1 of
the "Life and Letters." Published by D. Appleton & Co.]

It was evident that such facts as these, as well as many others, could
only be explained on the supposition that species gradually become
modified; and the subject haunted me. But it was equally evident that
neither the action of the surrounding conditions, nor the will of the
organisms (especially in the case of plants), could account for the
innumerable cases in which organisms of every kind are beautifully
adapted to their habits of life; for instance, a woodpecker or a
tree-frog to climb trees, or a seed for dispersal by hooks or plumes.
I had always been much struck by such adaptations, and until these
could be explained it seemed to me almost useless to endeavor to
prove by indirect evidence that species have been modified.

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 variation of animals and plants under domestication and
nature, some light might perhaps be thrown on the whole subject. My
first notebook 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 inquiries, by conversation with skilful breeders and
gardeners, and by extensive reading. When I set the list of books of
all kinds which I read and abstracted, including whole series of
Journals and Transactions, I am surprized 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 inquiry--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 favorable variations would tend to be preserved,
and unfavorable 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.
I