If you throw light on the want of geological time, may honour, eternal glory and blessings crowd thick on your head.—­Yours most sincerely,

CH.  DARWIN.

I forgot to say that I wrote to Dr. M. to say that I should not soon be in London, and that, of all things in the world, I hate most the bother of sitting for photographs, so I declined with many apologies.  I have recently refused several applications.

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9 St. Mark’s Crescent, N.W.  January 22, 1870.

Dear Darwin,—­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.

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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 right, and that they will do our cause much good.