To Charles Lyell   8[–9] September [1866]1

Down. | Bromley. | Kent. S.E.

Sep 8

My dear Lyell

It has been a great disappointmt to me putting off your visit; as it has proved we might have had you.2

My sister’s state varies a little but she suffers greatly & there is no hope of recovery.3

We are very glad that you think you will be able to come here in Oct.4

Many thanks for the pamphlet which was returned this mg.5 I was very glad to read it, though chiefly as a psychological curiosity. I quite follow you in thinking Agassiz glacier-mad. His evidence reduces itself to supposed moraines which wd be difficult to trace in a forest-clad country; & with respect to boulders, these are not said to be angular & their source cannot be known in a country so imperfectly explored. When I was at Rio I was continually astonished at the depth (sometimes 100 feet) to which the granitic rocks were decomposed in situ;6 & this soft matter wd easily give rise to great alluvial accumulations: I well remember finding it difficult to draw a line between the alluvial matter & the softened rock in situ.7 What a splendid imagination Agassiz has! & how energetic he is! What capital work he wd have done if he had sucked in your Principles with his mother’s milk.8 It is wonderful that he shd have written such wild nonsense about the valley of the Amazon; yet not so wonderful when one remembers that he once maintained before the Brit. Assoc that the chalk was all deposited at once.9

With respect to the insects of Chili, I knew only from Bates that the species of Carabus shewed no special affinity to northern species; from the great difference of climate & vegetation, I shd not have expected that many insects wd have shewn such affinity.10 It is more remarkable that the birds on the broad & lofty Cordillera of Tropical S. America shew no affinity with European species.11 The little power of diffusion with birds has often struck me as a most singular fact, even more singular than the great power of diffusion with plants. Remember that we hope to see you in the autumn

yours affectionately | Charles Darwin

Sunday Morning

P.S. I have just received a letter from Asa Gray with the following passage, so that according to this, I am the chief cause of Agassiz’ absurd views.12

“Agassiz is back (I have not seen him) & he went at once down to Nat. Accad. of Sciences—from which I sedulously keep away—& I hear proved to them that the Glacial period covered the whole continent of America with unbroken ice, & closed with a significant gesture & the remark, “So here is the end of the Darwin Theory”. How do you like that?

I said last winter, that Agassiz was bent on covering the whole continent with ice & that the motive of the discovery he was sure to make was to make sure that there shd be no coming down of any terrestrial life from tertiary or post-tertiary period to ours. You cannot deny that he has done his work effectually, in a truly imperial way.”

P.S. There is a capital paper in the Sept. nor of Annals & Mag, translated from Pictet & H. on fossil fish of Lebanon; but you will I daresay have received the original.— It is capital in relation to modification of species; I would not wish for more confirmatory facts, though there is no direct allusion to the modification of species.—13 Hooker, by the way, gave an admirable Lecture at Nottingham; I read it in M.S. or rather heard it.— I am glad it will be published, for it was capital.—14

LS(A)

1
The year is established by the relationship between this letter and the letter from Asa Gray, 27 August 1866. In 1866, 9 September was a Sunday.
2
No correspondence between CD and Lyell concerning the cancelled visit has been found. CD may have postponed a visit from Lyell owing to the severity of his sister’s illness (see n. 3, below).
3
Susan Elizabeth Darwin died on 3 October 1866 (Emma Darwin’s diary (DAR 242)).
4
Charles and Mary Elizabeth Lyell eventually visited the Darwins from 16 to 19 November 1866 (Emma Darwin’s diary (DAR 242)).
5
CD refers to an article by Louis Agassiz that appeared in two parts in Atlantic Monthly (J. L. R. Agassiz 1866a).
6
Agassiz put forward the theory that the Amazon valley had been covered by a glacier that had descended from the Cordilleras (the Andes mountains) to the west. He conceded that he had not found any of the characteristic traces of glacier movement, but claimed that the tropical climate was responsible for the decomposition of rocks that would have shown such evidence (J. L. R. Agassiz 1866a, pp. 162–3). In a series of lectures given during the winter of 1864 to 1865, Agassiz, arguing against the theory of the transmutation of species, had hypothesised that a continental ice sheet in South America had destroyed all life, so there could be no connection between species of the past and those of the present (see Lurie 1960, p. 345).
7
In South America, pp. 143–4, CD had remarked that the depth of decomposed gneiss and other granitic rocks in the district of Rio de Janeiro was close to 100 feet. Agassiz had admitted that the depth of decomposition of underlying rock made it difficult to distinguish between it and the drift (J. L. R. Agassiz 1866a, p. 50).
8
CD refers to Principles of geology (C. Lyell 1830–3). Lyell’s book had made a great impression on CD when he took the first volume of it on the Beagle voyage (see Autobiography, p. 77).
9
CD may be referring to the 1840 meeting of the British Association for the Advancement of Science, at which he met Agassiz (Lurie 1960, p. 100). At this meeting, Agassiz gave a paper on glaciers in Switzerland that summarised his book on the topic (J. L. R. Agassiz 1840a, 1840b). Lyell gave a paper, ‘On ancient sea cliffs and needles in the chalk of the valley of the Seine in Normandy’, in which he hypothesised that the valley was excavated during the slow and intermittent upheaval of land from the sea, resulting in several distinct levels of cliffs (C. Lyell 1840, p. 113). Agassiz may have made a remark about chalk deposition in discussion following Lyell’s paper.
10
In his article, Agassiz had remarked on the scarcity of insects in general and beetles in particular in the Amazon valley, but had not commented on differences of genera in different locations (J. L. R. Agassiz 1866a, p. 59). Henry Walter Bates had earlier informed CD about a Chilean subgenus of the beetle genus Carabus that he described as being quite distinct from all other species. See Correspondence vol. 10, letter from H. W. Bates, 30 April 1862 and n. 3, and letter to H. W. Bates, 4 May [1862] and n. 5. In Origin 4th ed., p. 454, CD speculated that the distinctiveness of the Chilean beetles indicated that their ancestors had been introduced at some very early period.
11
Agassiz had noted striking differences in gallinaceous birds of the Amazon valley compared with those in the rest of the world (J. L. R. Agassiz 1866a, p. 59).
12
CD copied the passage, with minor alterations, from the letter from Asa Gray, 27 August 1866.
13
The article in the Annals and Magazine of Natural History on fossil fishes referred to the ‘study of organic development throughout the course of geological time’ (Pictet de la Rive and Humbert 1866, p. 242), suggesting a tacit acceptance that some fish species had been modified over time, but it made no specific reference to the theory of the transmutation of species. CD’s annotated copy is among his unbound journals in the Darwin Library–CUL.
14
CD refers to Joseph Dalton Hooker’s lecture on insular floras delivered on 27 August 1866 at the meeting of the British Association for the Advancement of Science and later published in Gardeners’ Chronicle (J. D. Hooker 1866a). For the publication details of Hooker’s lecture, see the letter from J. D. Hooker, [28 August] 1866, n. 3.

Manuscript Alterations and Comments

11.1 P.S. There is … capital.—- 11.6] in CD’s hand
11.1 the Sept.] after del illeg
11.4 of species 11.5] interl

Please cite as “DCP-LETT-5208,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-5208