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Darwin Correspondence Project

To Asa Gray   24 December [1859]1

Down Bromley Kent

Dec. 24th

My dear Gray

I have been for 10 weeks at Water Cure & on my return a fortnight ago through London I found a copy of your Memoir, & heartily do I thank you for it.2 I have not read it, & shall not be able very soon, for I am much overworked & my stomach has got nearly as bad as ever.

With respect to the discussion on climate, I beg you to believe that I never put myself for a moment in competition with Dana; but when one has thought on subject, one cannot avoid forming some opinion.3 What I wrote to Hooker I forget, after reading only a few sheets of your memoir, which I saw would be full of interest to me.4 Hooker asked me to write to you, but as I told him, I would not presume to express an opinion to you without careful deliberation. What he wrote I know not.— I had previously several years ago seen (by whom I forget) some speculation on warmer period in U. States subsequent to Glacial period; & I had consulted Lyell who seemed much to doubt, & Lyell’s judgment is really admirably cautious.— The arguments advanced in your paper & in your letter seem to me hardly sufficient; not that I shd be at all sorry to admit this subsequent & intercalated warmer period—the more changes the merrier I think.—

On the other hand I do not believe that introduction of Old world forms into New world subsequent to Glacial period will do for the modified or representative forms in the Two Worlds; there has been too much change in comparison with the little change of isolated Alpine forms; but you will see this in my Book.—

I may just make a few remarks, why at first sight I do not attach much weight to the argument in your letter about the warmer climate. Firstly about the level of the land having been lower subsequently to Glacial period, as evidenced by the whole &c.5 I doubt whether metereological knowledge is sufficient for this deduction: turning to the S. hemisphere it might be argued that a greater extent of water made the temperature lower. And when much of the northern land was lower, it would have been covered by the sea & intermigration between old & new worlds would have been checked. Secondly I doubt whether any inference on nature of climate can be deduced from extinct species of Mammals. If the musk-ox & deer of great size of your Barren Grounds had been known only by fossil bones, who would have ventured to surmise the excessively cold climate they lived under. With respect to food of large animals, if you care about the subject, will you turn to my discussion on this subject partly in respect to the Elephas primigenius in my Journal of Researches (Murray’s Home & Colonial Library) Ch V. p. 85.— In this country we infer from remains of Elephas primegenius, that the climate at the period of its embedment was very severe, as seems countenanced by its woolly covering,—by the nature of the deposit with angular fragments,—the nature of the coembedded shells, & coexistence of the Musk Ox. I had formerly gathered from Lyell that the relative position of Megatherium & Mylodon with respect to the Glacial deposits, had not been well made out; but perhaps it has been so recently.— Such are my reasons for not as yet admitting the warmer period subsequent to Glacial epoch; but I daresay I may be quite wrong, & shall not be at all sorry to be proved so.—

I shall assuredly read your Essay with care, for I have seen as yet only a fragment; & very likely some parts, which I could not formerly clearly understand, will be clear enough.— And I am very sorry that Hooker said a word about my opinion.—6

I have been much interested by all that you say in early part of letter about “Creation” & the philosophy of the subject. As you truly remark, if one admits a certain amount of creation there is no obvious reason why not admit many acts.— But I rest on the fact that the theory of Natural selection explains many classes of facts, which, as far as we can see, repeated acts of Creation do not explain. On this latter view we can only say “so it is” & not at all “why it is so”.— Pray do not decide either way till you have read Ch. XIII & the Recapitulation (Ch XIV) which will, I think, aid you in balancing facts.— I value your opinion most highly; & I hope you will not think me presumptuous in saying how sincerely I have admired your several letters to me & some to Hooker which I have occasionally read. I am rejoiced to say that Lyell is a complete convert; & is heroic & candid enough to be now writing a public change of opinion.— Huxley, a first-rate zoologist, & Carpenter first-rate physiologist are converts; as is H. C. Watson. So that I am more than contented. I am sure to be in error in many parts; but my general view, I conclude, must have some truth in it.— There are however many bitter opponents. I sent the copy of my Book through Murray. I had written out the Forbesian doctrine of Alpine plants 4 years before Forbes published, as Hooker knew, but I do not believe that Forbes had ever heard of it: so he is originator, as you will see in my Book, I do not allude to my prior work in M.S.7

My dear Gray | Yours most sincerely | C. Darwin

Murray writes he sent my Book by Steamer Dec 3. & has now sent off clean sheets of the Reprint, as much as is yet printed.8


Dated by the relationship to the letters to Asa Gray, 21 December [1859], and to John Murray,22 December [1859].
A. Gray 1858–9. There is an annotated copy of the paper in the Darwin Pamphlet Collection–CUL.
The point at issue was whether there was sufficient geological evidence to indicate that there had been a warm period after the glacial era as well as before. James Dwight Dana believed that there were clear signs of a post-glacial warm period, and Gray used this information to explain the apparent mingling of Arctic and northern floras (A. Gray 1858–9, p. 447). CD had discussed the point with Joseph Dalton Hooker (letter to J. D. Hooker, 11 May [1859], and letter from J. D. Hooker,[20 December 1859]), and with Gray (see letter to Asa Gray, 11 August [1858]).
Hooker had sent CD the concluding section of A. Gray 1858–9, which discussed the geological evidence that possibly explained the relation between the flora of Japan and that of the north-eastern region of the United States. CD had also read the preliminary remarks that Gray had made at a meeting of the American Academy of Arts and Sciences in Boston in January 1859 (see letter to J. D. Hooker, 3 May [1859]).
A. Gray 1859, pp. 447–8.
In a letter to Asa Gray, 31 May 1859 (Gray Herbarium, Harvard University), Hooker praised A. Gray 1859 but stated: ‘Your Geological distribution we cannot follow at all, & Darwin & I both doubt your Geological facts, especially the Zoological Palæontology.’ See also letter to J. D. Hooker, 28 [December 1859].
In his letter to Asa Gray, 11 August [1858], CD outlined his views on a former worldwide cold-period, mentioning that he had written these out four years before a similar theory was published by Edward Forbes (Forbes 1846). Gray had taken this to mean that CD was the originator of the theory and implied this in A. Gray 1858–9.
See letters to John Murray, 22 December [1859] and 24 December [1859].


Forbes, Edward. 1846. On the connexion between the distribution of the existing fauna and flora of the British Isles, and the geological changes which have affected their area, especially during the epoch of the Northern Drift. Memoirs of the Geological Survey of Great Britain, and of the Museum of Economic Geology in London 1: 336–432.

Gray, Asa. 1858–9. Diagnostic characters of new species of phænogamous plants, collected in Japan by Charles Wright, botanist of the US North Pacific Exploring Expedition … With observations upon the relations of the Japanese flora to that of North America, and of other parts of the northern temperate zone. [Read 14 December 1858 and 11 January 1859.] Memoirs of the American Academy of Arts and Sciences n.s. 6: 377–452.

Gray, Asa. 1859. On the coiling of tendrils. American Journal of Science and Arts 2d ser. 27: 277–8. [Vols. 10,11]


Thanks for AG’s Japan memoir [Mem. Am. Acad. Arts & Sci. 6 (1857–9): 377–452]. Does not think AG’s arguments for a warm post-glacial period are sufficient, but will not be sorry to be proved wrong.

Believes natural selection explains many classes of facts which repeated creation does not.

Writes of some responses to the Origin.

Letter details

Letter no.
Charles Robert Darwin
Asa Gray
Sent from
Source of text
Archives of the Gray Herbarium, Harvard University (46)
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 2599,” accessed on 24 September 2023,

Also published in The Correspondence of Charles Darwin, vol. 7