Down, Beckenham, Kent.  November 3, 1880.

My dear Wallace,—­I have now read your book,[113] and it has interested me deeply.  It is quite excellent, and seems to me the best book which you have ever published; but this may be merely because I have read it last.  As I went on, I made a few notes,[114] chiefly when I differed strongly from you; but God knows whether they are worth your reading.  You will be disappointed with many of them; but they will show that I had the will, though I did not know the way, to do what you wanted.

I have said nothing on the infinitely many passages and views which I admired and which were new to me.  My notes are badly expressed; but I thought that you would excuse my taking any pains with my style.  I wish that my confounded handwriting was better.

I had a note the other day from Hooker, and I can see that he is much pleased with the Dedication.

With all good wishes, believe me yours sincerely,

CH.  DARWIN.

In two or three weeks you will receive a book from me; if you care to know what it is about, read the paragraph in Introduction about new terms and then the last chapter, and you will know whole contents of book.

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Pen-y-bryn, St. Peter’s Road, Croydon.  November 8, 1880.

My dear Darwin,—­Many thanks for your kind remarks and notes on my book.  Several of the latter will be of use to me if I have to prepare a second edition, which I am not so sure of as you seem to be.

1.  In your remark as to the doubtfulness of paucity of fossils being due to coldness of water, I think you overlook that I am speaking only of waters in the latitude of the Alps, in Miocene and Eocene times, when icebergs and glaciers temporarily descended into an otherwise warm sea; my theory being that there was no glacial epoch at that time, but merely a local and temporary descent of the snow-line and glaciers owing to high excentricity and winter in aphelion.

2.  I cannot see the difficulty about the cessation of the glacial period.  Between the Miocene and the Pleistocene periods geographical changes occurred which rendered a true glacial period possible with high excentricity.  When the high excentricity passed away the glacial epoch also passed away in the Temperate zone; but it persists in the Arctic zone, where during the Miocene there were mild climates, and this is due to the persistence of the changed geographical conditions.  The present Arctic climate is itself a comparatively new and abnormal state of things due to geographical modification.  As to “epoch” and “period,” I use them as synonyms to avoid repeating the same word.