My dear Sir Charles,

I take advantage of my first quiet day to reply to your letter of the
9th; and in the first place let me thank you very much for your critical
remarks, as I shall find them of great service.

With regard to such matters as verbal mistakes, you must recollect that
the greater part of the proof was wholly uncorrected. But the reader
might certainly do his work better. I do not think you will find room to
complain of any want of distinctness in my definition of Owen's position
touching the Hippocampus question. I mean to give the whole history of
the business in a note, so that the paraphrase of Sir Philip Egerton's
line "To which Huxley replies that Owen he lies," shall be unmistakable.

I will take care about the Cheiroptera, and I will look at Lamarck
again. But I doubt if I shall improve my estimate of the latter. The
notion of common descent was not his--still less that of modification by
variation--and he was as far as De Maillet from seeing his way to any
vera causa by which varieties might be intensified into species.

If Darwin is right about natural selection--the discovery of this vera
causa sets him to my mind in a different region altogether from all his
predecessors--and I should no more call his doctrine a modification of
Lamarck's than I should call the Newtonian theory of the celestial
motions a modification of the Ptolemaic system. Ptolemy imagined a mode
of explaining those motions. Newton proved their necessity from the laws
and a force demonstrably in operation. If he is only right Darwin will,
I think, take his place with such men as Harvey, and even if he is wrong
his sobriety and accuracy of thought will put him on a far different