I am so much weaker in the head, that I hardly know if I can write, but at
all events I will jot down a few things that the Dr. (Dr., afterwards Sir
Henry Holland.) has said. He has not read much above half, so as he says
he can give no definite conclusion, and it is my private belief he wishes
to remain in that state...He is evidently in a dreadful state of
indecision, and keeps stating that he is not tied down to either view, and
that he has always left an escape by the way he has spoken of varieties. I
happened to speak of the eye before he had read that part, and it took away
his breath--utterly impossible--structure, function, etc., etc., etc., but
when he had read it he hummed and hawed, and perhaps it was partly
conceivable, and then he fell back on the bones of the ear, which were
beyond all probability or conceivability. He mentioned a slight blot,
which I also observed, that in speaking of the slave-ants carrying one
another, you change the species without giving notice first, and it makes
one turn back...

...For myself I really think it is the most interesting book I ever read,
and can only compare it to the first knowledge of chemistry, getting into a
new world or rather behind the scenes. To me the geographical
distribution, I mean the relation of islands to continents, is the most
convincing of the proofs, and the relation of the oldest forms to the
existing species. I dare say I don't feel enough the absence of varieties,
but then I don't in the least know if everything now living were fossilized
whether the paleontologists could distinguish them. In fact the a priori
reasoning is so entirely satisfactory to me that if the facts won't fit in,
why so much the worse for the facts is my feeling. My ague has left me in
such a state of torpidity that I wish I had gone through the process of
natural selection.

Yours affectionately,