opposed to my general results, to make a memorandum
of it without fail and at once; for I had found by experience that such
facts and thoughts were far more apt to escape from the memory than
favorable ones. Owing to this habit, very few objections were raised
against my views which I had not at least noticed and attempted to
answer.

It has sometimes been said that the success of the _Origin_ proved "that
the subject was in the air," or "that men's minds were prepared for it."
I do not think that this is strictly true, for I occasionally sounded
not a few naturalists, and never happened to come across a single one
who seemed to doubt about the permanence of species. Even Lyell and
Hooker, though they would listen with interest to me, never seemed to
agree. I tried once or twice to explain to able men what I meant by
"natural selection," but signally failed. What I believe was strictly
true is that innumerable well-observed facts were stored in the minds of
naturalists ready to take their proper places as soon as any theory that
would receive them was sufficiently explained. Another element in the
success of the book was its moderate size; and this I owe to the
appearance of Mr. Wallace's essay; had I published on the scale in which
I began to write in 1856, the book would have been four or five times as
large as the _Origin_, and very few would have had the patience to read
it. I gained much by my delay in publishing from about 1839, when the
theory was clearly conceived, to 1859; and I lost nothing by it, for I
cared very little whether men attributed more originality to me or to
Wallace; and his essay no doubt aided in the reception of the theory. I
was forestalled in only one important point, which my vanity has always
made me regret, namely, the explanation, by means of the Glacial period,
of the presence of the same species of plants and of some few animals on
distant mountain summits and in the arctic regions. This view pleased me
so much that I wrote it out _in extenso_, and I believe that it was read
by Hooker some years before Edward Forbes published his celebrated
memoir on the subject. In the very few points in which we differed I
still think that I was in the right. I have never, of course, alluded in
print to my having independently worked out this view.

Hardly any point gave me so much satisfaction, when I was at work on the
_Origin_, as the explanation of the wide difference in many classes
between the