To Fritz Müller   2 August [1871]¹

My dear Sir

Your last letter has interested me greatly: it is wonderfully rich in facts & original thoughts.² First let me say that I have been much pleased by what you say about my book. It has had a very large sale, but I have been much abused for it, especially for the chapter on the moral sense; & most of my Reviewers consider the book as a poor affair.³ God knows what its merits may really be; all that I know is that I did my best. With familiarity I think naturalists will accept sexual selection to a greater extent than they now seem inclined to do.— I sh^d. very much like to publish your letter, but I do not see how it could be made intelligible without numerous coloured illustrations; but I will consult M^r Wallace on this head.⁴ I earnestly hope that you keep notes of all your letters & that some day you will publish a book “Notes of a Naturalist in S. Brazil” or some such title.⁵ Wallace will hardly admit the possibility of sexual selection with Lepidoptera, & no doubt it is very improbable—⁶ Therefore I am very glad to hear of your cases (which I will quote in next Edition) of the 2 sets of Hesperiadæ, which display their wings differently according to which surface is coloured.⁷ I cannot believe that such display is accidental & purposeless. Will you have the kindness to inform me, whether the yellow & white Hedychiums &c which are not visited by certain Butterflies are distinct species or mere varieties;— I suppose the former.⁸

No part of your letter has interested me more than that about mimicry. It is a capital fact about the males pursuing the wrong females.⁹ You put the difficulty of the first steps in imitation in a most striking & convincing manner. Your idea of sexual selection having aided protective imitation interests me greatly, for the same idea had occurred to me in quite different cases, viz the dullness of all animals in the Galapagos Isl^d, Patagonia &c. & in some other cases; but I was afraid even to hint at such an idea.— Would you object to my giving some such sentence as follows “F. Müller suspects that sexual selection may have come into play, in aid of protective imitation, in a very peculiar manner, which will appear extremely improbable to those who do not fully believe in sexual selection. It is that the appreciation of certain colours is developed in those species which frequently behold other species thus ornamented”.¹⁰ Again let me thank you cordially for your most interesting letter.—

The Abutilon turns out a new species, which Hooker is going to name, figure & describe.¹¹ The seedlings were several weeks absolutely sterile with own flowers pollen & pollen from same plant, & fertile with pollen from any other plant. But after several weeks they became fertile in moderate degree with own flower’s pollen!¹² I have seen other cases of this.— I have been suffering of late a good deal from ill-health, & have stopped all work, & am writing this away from my home.—¹³ On my return in a month’s time I must prepare a new Edit. of the Origin, which I will send you when published..—¹⁴

Believe me | Yours most sincerely | Ch. Darwin