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Darwin Correspondence Project

To George Bentham   22 May [1863]1

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

May 22d

My dear Bentham

I am much obliged for your kind & interesting letter.2 I have no fear of anything that a man like you, will say annoying me in the very least degree.3 On the other hand any approval from one, whose judgment & knowledge I have for many years so sincerely respected, will gratify me much.— The objection, which you well put, of certain forms remaining unaltered through long time & space, is no doubt formidable in appearance & to a certain extent in realility according to my judgment.—4 But does not the difficulty rest much on our silently assuming that we know more than we do? I have literally found nothing so difficult as to try & always remember our ignorance. I am never weary when walking in any new adjoining district or country of reflecting how absolutely ignorant we are why certain old plants are not there present, & other new ones are & others in different proportions. If we once fully feel this, then in judging the theory of natural selection, which implies that a form will remain unaltered unless some alteration be to its benefit, is it so very wonderful that some forms should change much slower & much less, & some few should have changed not at all under conditions which to us (who really know nothing what are the important conditions) seem very different.— Certainly a priori we might have anticipated that all the plants anciently introduced into Australia would have undergone some modification; but the fact that they have not been modified does not seem to me a difficulty of weight enough to shake a belief grounded on other arguments.— I have expressed myself miserably, but I am far from well today.—

I am very glad that you are going to allude to Pasteur; I was struck with infinite admiration at his work.—5

With cordial thanks, believe me Dear Bentham | Yours very sincerely | Ch. Darwin

In fact the belief in natural selection must at present be grounded entirely on general considerations. (1) on its being a vera causa, from the struggle for existence; & the certain geological fact that species do somehow change (2) from the analogy of change under domestication by man’s selection. (3) & chiefly from this view connecting under an intelligible point of view a host of facts.—

When we descend to details, we can prove that no one species has changed: nor can we prove that the supposed changes are beneficial which is the groundwork of the theory. Nor can we explain why some species have changed & others have not. The latter case seems to me hardly more difficult to understand precisely & in detail than the former case of supposed change. Bronn may ask in vain the old creationist school & the new school why one mouse has longer ears than another mouse—& one plant more pointed leaves than another plant.—6


The year is established by the relationship between this letter and the letter from George Bentham, 21 May 1863.
Bentham was preparing his anniversary address as president of the Linnean Society, to be delivered on 25 May 1863 (Bentham 1863). See letter from George Bentham, 21 May 1863.
See letter from George Bentham, 21 May 1863 and n. 7. Although there are no publications by Louis Pasteur in the Darwin Library, CD was evidently familiar with his prize-winning essay, ‘Mémoire sur les corpuscules organisés qui existent dans l’atmosphère’ (Pasteur 1861). See Correspondence vol. 10, letter from Henry Holland, [c. April 1862] and n. 4.
CD refers to the critical discussion that Heinrich Georg Bronn added at CD’s suggestion (see Correspondence vol. 8, letter to H. G. Bronn, 4 February [1860]) to his German translation of Origin (Bronn trans. 1860, pp. 503–5). CD prepared a four-page list of Bronn’s criticisms, which is appended to his copy of Bronn trans. 1860 in the Darwin Library–CUL (see Correspondence vol. 8, letter to H. G. Bronn, 5 October [1860], CD note, and Marginalia 1: 180–2). These criticisms were addressed in the third and later editions of Origin. For CD’s treatment of this specific point, see Peckham ed. 1959, p. 232. See also Correspondence vol. 8, letter to H. G. Bronn, 5 October [1860], and letter to Charles Lyell, 8 October [1860].


Bentham, George. 1863. [Anniversary address, 25 May 1863.] Journal of the Proceedings of the Linnean Society (Botany) 7 (1864): xi–xxix.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.

Pasteur, Louis. 1861. Mémoire sur les corpuscules organisés qui existent dans l’atmosphère, examen de la doctrine des générations spontanées. Annales des Sciences Naturelles (Zoologie) 4th ser. 16: 5–98. [Vols. 10,11]


Natural selection implies that a form remains unaltered unless an alteration is to its benefit. This is not inconsistent with some forms remaining stable for long periods. Natural selection must at present be grounded entirely on general considerations. Of details we are still greatly ignorant.

Please cite as

Darwin Correspondence Project, “Letter no. 4176,” accessed on 21 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 11