To B. D. Walsh   23 March [1867]1

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

March 23d

My dear Sir

I am a good deal overworked with the tedious labour of correcting the proofs of my new book, but I cannot resist sending you a few lines to thank you for pleasant & kind letter of Feb 25th—2 I quite agree with what you say about the high value of disseminating scientific knowledge,—perhaps as useful as mere discovery—only you should remember that there are many who can do the one & only a few who can discover original truths.—3 Thanks for Lecture of Agassiz.4 Lyell does not believe a word about glacial action of any kind in lowlands of Brazil. If anyone had attempted to prove, even in a temperate region, former glacial action, & had owned he could find no striæ, he wd. have been laughed at.—5

I believe that the theory that glaciers are propelled by alternate freezing & thawing has been given up by all physicists.—6

I did not know about the workers’ wasps breeding.—7

My new Book will interest you or any one else very little: it will not appear till November & will be entitled “The Variation of Animals & Plants under Domestication”.—8

With many thanks for your letter—

Believe me, yours very sincerely | Ch. Darwin

1
The year is established by the reference to Variation (see nn. 2 and 8, below).
2
See letter from B. D. Walsh, [25 February 1867]. CD had received the first proof-sheets of Variation on 1 March 1867 (CD’s ‘Journal’ (Correspondence vol. 15, Appendix II)).
3
Walsh had defended his decision to become editor of Practical Entomologist on the grounds that it would promote the pursuit of science in America (see letter from B. D. Walsh, [25 February 1867]).
4
CD refers to Louis Agassiz and the lecture on glaciers in J. L. R. Agassiz 1867. See letter from B. D. Walsh, [25 February 1867] and n. 4.
5
Agassiz advanced the hypothesis that the Amazon valley had been covered by a huge glacier in J. L. R. Agassiz 1866. CD had discussed Agassiz’s claims regarding glacial action in Brazil with Charles Lyell and other correspondents (see Correspondence vol. 14).
6
For a summary of contemporary views on the causes of glacier movement, see C. Lyell 1867–8, 1: 369–74. For CD’s earlier discussion of the topic, see Correspondence vol. 6, letter to T. H. Huxley, 17 January [1857].
8
Variation was published in January 1868 (Freeman 1977).

Please cite as “DCP-LETT-5455,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-5455