My dear M^r Kingsley

I have been deeply interested by your letter. I have looked through my whole large collection of pamphlets on the “Origin” & the only thing which I can find at all answering to y^r description is that which I send by this post by Cap. Hutton. I dare say you know his name; he is a very acute observer. Please sometime return it to me.²

I have just finished reading the Duke’s book & N. Brit. Rev.;³ & I sh^d very much like for my own sake to make some remarks on them, & as my amanuensis⁴ writes so clearly, I hope it will not plague you. The Duke’s book strikes me as very well written, very interesting, honest & clever & very arrogant. How coolly he says that even J. S. Mill does not know what he means.⁵ Clever as the book is, I think some parts are weak, as about rudimentary organs,⁶ & about the diversified structure of humming birds. How strange it is that he sh^d freely admit that every detail of structure is of service in the flowers of orchids, & not in the beak of birds. His argument with respect to diversity of structure is much the same as if he were to say that a mechanic w^d succeed better in England if he c^d do a little work in many trades, than by being a first-rate workman in one trade.⁷ I sh^d like you to read what I have said upon diversity of structure at 226 in the new Ed. of Origin,⁸ which I have ordered to be sent to you. Please also read what I have said (p. 238) on Beauty.) Other explanations with respect to beauty will no doubt be found out: I think the enclosed ingenious letter by Wallace is worth y^r notice.⁹ Is is not absurd to speak of beauty as existing independently of any sentient being to appreciate it? And yet the Duke seems to me thus to speak. With respect to the Deity having created objects beautiful for his own pleasure, I have not a word to say against it but such a view c^d hardly come into a scientific book. In regard to the difference between female birds I believe what you say is very true; & I can shew with fowls that the 2 sexes often vary in correlation.¹⁰ I am glad that you are inclined to admit sexual selection. I have lately been attending much to this subject, & am more than ever convinced of the truth of the view. You will see in the discussion on beauty that I allude to the cause of female birds not being beautiful; but Mr Wallace is going to generalize the same view to a grand extent, for he finds there is almost always a relation between the nature of the nest & the beauty of the female.¹¹

No doubt sexual selection seems very improbable when one looks at a peacock’s tail, but it is an error to suppose that the female selects each detail of colour. She merely selects beauty, & laws of growth determine the varied zones of colour: thus a circular spot w^d almost certainly become developed into circular zones, in the same manner as I have seen the black wing-bar in pigeons become converted into 3 bars of colour elegantly shaded into each other. The Duke is not quite fair in his attack on me with respect to “correlation of growth”; for I have defined what I mean by it, tho’ the term may be a bad one, whilst he uses another definition: “correlation of variation” w^d perhaps have been a better term for me.¹² He depreciates the importance of natural selection, but I presume he w^d not deny that Bakewell, Collins, &c had in one sense made our improved breeds of cattle,¹³ yet of course the initial variations have naturally arisen; but until selected, they remained unimportant, & in this same sense natural selection seems to me all-important.

The N. Brit. Rev. seems to me one of the most telling Reviews of the hostile kind, & shews much ability, but not, as you say, much knowledge. The R. lays great stress on our domestic races having been rapidly formed, but I can shew that this is a complete error; it is the work of centuries, probably in some cases of 1000s of years.¹⁴ With respect to the antiquity of the world & the uniformity of its changes, I cannot implicitly believe the mathematicians, seeing what widely different results Haughton Hopkins & Thompson have arrived at.¹⁵ By the way I had a note from Lyell this m^g. who does not seem to value this article enough.¹⁶

Is there not great doubt on the bearing of the attraction of gravity with respect to the conservation of energy? The glacial period may make one doubt whether the temperature of the universe is so simple a question. No one can long study the Geolog. work done during the glacial period, & not end profoundly impressed with the necessary lapse of time; & the crust of the earth was at this recent period as thick as now & the force of Nature not more energetic. But what extremely concerns me, is R. statement that I require million of years to make new species; but I have not said so, on contrary, I have lately stated that the change is probably rapid both in formation of single species & of whole groups of species, in comparison with the duration of each species when once formed or in comparison with the time required for the development of a group of species—¹⁷ with respect to Classification, it is the idea of a natural classification, which the genealogical explains.¹⁸ The best bit of Review, which c^d make me modify wording of few passages in origin is I think about sudden sports, & these I have always thought, but now more clearly see, w^d generally be lost by crossing.¹⁹ The R does not however notice, that any variation w^d. be more likely to recur in crossed offspring still exposed to same conditions, as those which first caused the parent to vary.— I have moreover expressly stated that I do not believe in the sudden deviation of structure under nature, such as occurs under dom: but I weakened the sentence in deference to Harvey.—²⁰

When speaking of the formation for instance of a new sp. of Bird with long beak Instead of saying, as I have sometimes incautiously done a bird suddenly appeared with a beak [particularly] longer than that of his fellows, I would now say that of all the birds annually born, some will have a beak a shade longer, & some a shade shorter, & that under conditions or habits of life favouring longer beak, all the individuals, with beaks a little longer would be more apt to survive than those with beaks shorter than average.²¹

The preservation of the longer-beaked birds, would in addition add to the augmented tendency to vary in this same direction.— I have given this idea, but I have not done so in a sufficiently exclusive manner.— The Reviewer w^d have left his article stronger if he had not attempted to exclusively grapple with the [illeg] problem of [variation] ²²

⁠⟨⁠missing text⁠⟩⁠ of facts. Pray excuse this unreasonable letter, which you may not think worth the labour of reading; but it has done me good to express my opinion on the 2 works in question, so I hope & think that you will forgive me—

With very sincere thanks for letter believe me my dear M^r Kingsley | yours sincerely | Charles Darwin

Do you know who wrote the article in N. B. Review?²³