I look at it as immaterial whether we go quite the same lengths; and I
suspect, judging from myself, that you will go further, by thinking of a
population of forms like Ornithorhyncus, and by thinking of the common
homological and embryological structure of the several vertebrate orders.
But this is immaterial. I quite agree that the principle is everything.
In my fuller MS. I have discussed a good many instincts; but there will
surely be more unfilled gaps here than with corporeal structure, for we
have no fossil instincts, and know scarcely any except of European animals.
When I reflect how very slowly I came round myself, I am in truth
astonished at the candour shown by Lyell, Hooker, Huxley, and yourself. In
my opinion it is grand. I thank you cordially for taking the trouble of
writing a review for the 'National.' God knows I shall have few enough in
any degree favourable. (See a letter to Dr. Carpenter below.)


CHARLES DARWIN TO C. LYELL.
Saturday [December 5th, 1859].

...I have had a letter from Carpenter this morning. He reviews me in the
'National.' He is a convert, but does not go quite so far as I, but quite
far enough, for he admits that all birds are from one progenitor, and
probably all fishes and reptiles from another parent. But the last
mouthful chokes him. He can hardly admit all vertebrates from one parent.
He will surely come to this from Homology and Embryology. I look at it as
grand having brought round a great physiologist, for great I think he
certainly is in that line. How curious I shall be to know what line Owen
will take; dead against us, I fear; but he wrote me a most liberal note on
the reception of my book, and said he was quite prepared to consider fairly
and without prejudice my line of argument.