-My paper on Geological Time having been in type nearly two
months, and not knowing when it will appear, I have asked for a proof to
send you, Huxley and Lyell. The latter part only contains what I think
is new, and I shall be anxious to hear if it at all helps to get over
your difficulties.

I have been lately revising and adding to my various papers bearing on
the "Origin of Species," etc., and am going to print them in a volume
immediately, under the title of "Contributions to the Theory of Natural
Selection: A Series of Essays."

In the last, I put forth my heterodox opinions as to Man, and even
venture to attack the Huxleyan philosophy!

Hoping you are quite well and are getting on with your Man book, believe
me, dear Darwin, yours very faithfully,

ALFRED R. WALLACE.

P.S.--When you have read the proof and done with it, may I beg you to
return it to me?--A.R.W.

* * * * *

_Down, Beckenham, Kent, S.E. January 26, [1870]._

My dear Wallace,--I have been very much struck by your whole article
(returned by this post), especially as to rate of denudation, for the
still glaciated surfaces have of late most perplexed me. Also
_especially_ on the lesser mutations of climate during the last 60,000
years; for I quite think with you no cause so powerful in inducing
specific changes, through the consequent migrations. Your argument would
be somewhat strengthened about organic changes having been formerly more
rapid, if Sir W. Thomson is correct that physical changes were formerly
more violent and abrupt.

The whole subject is so new and vast that I suppose you hardly expect
anyone to be at once convinced, but that he should keep your view before
his mind and let it ferment. This, I think, everyone will be forced to
do. I have not as yet been able to digest the fundamental notion of the
shortened age of the sun and earth. Your whole paper seems to me
admirably clear and well put. I may remark that Ruetimeyer has shown that
several wild mammals in Switzerland since the neolithic period have had
their dentition and, I _think_, general size _slightly_ modified. I
cannot believe that the Isthmus of Panama has been open since the
commencement of the glacial period; for, notwithstanding the fishes, so
few shells, crustaceans, and, according to Agassiz, not one echinoderm
is common to the sides. I am very glad you are going to publish all your
papers on Natural Selection: I am sure you are r