generally excites my admiration, and it is only after
considerable reflection that I perceive the weak points. My
power to follow a long and purely abstract train of thought is
very limited; and therefore I could never have succeeded with
metaphysics or mathematics. My memory is extensive, yet hazy:
it suffices to make me cautious by vaguely telling me that I have
observed or read something opposed to the conclusion which I am
drawing, or on the other hand in favour of it; and after a time I
can generally recollect where to search for my authority. So
poor in one sense is my memory, that I have never been able to
remember for more than a few days a single date or a line of
poetry.

Some of my critics have said, "Oh, he is a good observer, but he
has no power of reasoning!" I do not think that this can be
true, for the 'Origin of Species' is one long argument from the
beginning to the end, and it has convinced not a few able men.
No one could have written it without having some power of
reasoning. I have a fair share of invention, and of common sense
or judgment, such as every fairly successful lawyer or doctor
must have, but not, I believe, in any higher degree.

On the favourable side of the balance, I think that I am superior
to the common run of men in noticing things which easily escape
attention, and in observing them carefully. My industry has been
nearly as great as it could have been in the observation and
collection of facts. What is far more important, my love of
natural science has been steady and ardent.

This pure love has, however, been much aided by the ambition to