To G. H. K. Thwaites   21 March [1860]1

Down Bromley Kent

March 21st

My dear Mr. Thwaites

I thank you very sincerely for your letter & am much pleased that you go a little way with me.2 You will think it presumptuous, but I am well convinced from my own mental experience, that if you keep the subject at all before your mind, you will ultimately go further. The present vol. is mere abstract & there are great omissions— one main one, which I have rectified in the foreign Editions is an explanation (which has satisfied Lyell, who made same objection with you) why many forms do not progress or advance.3 (& I quite agree about some retrograding)— I have also M.S. discussion on beauty—but do you really suppose that for instance Diatomaceæ were created beautiful that man after millions of generations shd. admire them through the microscope?—4

I shd. attribute most of such structures to quite unknown laws of growth; & mere repetition of parts is to our eyes one main element of beauty. When any structure is of use (& I can show what curiously minute particulars are often of highest use) I can see with my prejudiced eyes no limit to the perfection of the coadaptations which could be effected by natural selection.—

I rather doubt whether you see how far, as it seems to me, the argument from Homology & Embryology may be carried. I do not look at this as mere analogy. I would as soon believe that fossil shells were mere mockeries of real shells, as that the same bones in foot of dog & wing of bat—or the similar embryo of mammal & bird—had not a direct signification & that signification can be unity of descent or nothing. But I venture to repeat how much pleased I am that you go some little way with me. I find a number of naturalists do the same, & as their halting places are various & I must think arbitrary, I believe they will all go further. As for changing at once ones opinion; I would not value the opinion of a man who could do so: it must be a slow process.—

Thank you for telling me about the Lantana;5 & I shd. at any time be most grateful for any information which you think would be of use to me.— I hope that you will publish a list of all naturalised plants in Ceylon, as far as known, carefully distinguishing those confined to cultivated soils alone. I feel sure that this most important subject has been greatly undervalued.

With hearty thanks for your letter | Believe me | Yours very sincerely | C. Darwin

CD note:6

March 21/60 Thwaites objects about the beauty of Diatomaceæ— was it created for man after millions of generations to admire through microscope. NB. mere symmetrical repetition is to us [‘one’ del] one main element of beauty & that no difficulty—mere vegetative repetition

1
The year is given by the relationship to the letter from G. H. K. Thwaites, [14 February 1860].
3
See letter to Charles Lyell, 18 [and 19 February 1860]. CD and Charles Lyell had discussed this topic during Lyell’s recent visit to Down. Lyell recorded in his scientific journal (Wilson ed. 1970, p. 359): Why so many simple beings still? Lamarck introdd. spontaneous generations, but Darwin’s natural selection implies no innate tendency to perfection & development is necessary. Rhizopods, or infusoria, foraminifera, have remained for several geologl. periods unchanged.
4
Thwaites was an expert on the Diatomaceae. In Origin, p. 199, CD briefly discussed the question of beauty as it related to selection, stating that some naturalists ‘believe that very many structures have been created for beauty in the eyes of man, or for mere variety. This doctrine, if true, would be absolutely fatal to my theory.’ Beautiful, though apparently useless, structures were discussed in detail in Descent.
5
Thwaites had told CD that Lantana aculeata, a species of Verbenaceae introduced to Ceylon, was spreading rapidly there (see letter from G. H. K. Thwaites, [14 February 1860]. See also ML 1: 145 n. 2.
6
The note is in DAR 48: 42. It is marked ‘Ch 8’ in brown crayon, a reference to chapter 8 of CD’s ‘big book’ on species (Natural selection), ‘Difficulties on the theory’.

Manuscript Alterations and Comments

1.7 (& I quite … retrograding)] interl
1.9 for instance Diatomacea+e] interl before del ‘they’
3.1 how far] after del ‘what I mean by the manner’
3.9 ones opinion;] interl

Please cite as “DCP-LETT-2731,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-2731