n June, 1842, I first allowed myself the satisfaction of writing a
very brief abstract of my theory in pencil in thirty-five pages; and
this was enlarged during the summer of 1844 into one of two hundred
and thirty pages, which I had fairly copied out and still possess.

But at that time I overlooked one problem of great importance; 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 suborders, and so
forth: and I can remember the very spot in the road, while 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 many and highly diversified places in the economy of
nature.

Early in 1856 Lyell advised me to write out my views pretty fully, and
I began at once to do so on a scale three or four times as extensive
as that which was afterward followed in my "Origin of Species"; yet it
was only an abstract of the materials which I had collected, and I got
through about half the work on this scale. But my plans were
overthrown, for early in the summer of 1858 Mr. Wallace, who was then
in the Malay Archipelago, sent me an essay "On the Tendency of
Varieties to Depart Indefinitely from the Original Type"; and this
essay contained exactly the same theory as mine. Mr. Wallace exprest
the wish that if I thought well of his essay, I should send it to
Lyell for perusal.

The circumstances under which I consented, at the request of Lyell and
Hooker, to allow of an abstract from my MS., together with a letter to
Asa Gray dated September 5th, 1857, to be published at the same time
with Wallace's essay, are given in the "Journal of the Proceedings of
the Linnean Society," 1858, page 45. I was at first very unwilling to
consent, as I thought Mr. Wallace might consider my doing so
unjustifiable, for I did not then know how generous and noble was his
disposition. The extract from my MS. and the letter to Asa Gray had
neither been intended for publication, and were badly written. Mr.
Wallace's essay, on the other hand,