My dear Lyell

I thank you for your very interesting letter.² I have the true English instinctive reverence for rank & therefore liked to hear about the Princess Royal.³ You ask what I think of the Duke’s address⁴ & I shall be glad to tell you.

It seems to me extremely clever like every thing that I have read of his; but I am not shaken; perhaps you will say that neither gods nor men could shake me. I demur to the Duke reiterating his objection that the brilliant plumage of the male humming bird could not have been acquired through selection, at the same time entirely ignoring my discussion (p. 93 3^rd Edition) on beautiful plumage being acquired thro’ sexual selection.⁵ The Duke may think this insufficient, but that is another question. All analogy makes me quite disagree with the Duke that the differences in the beak, wing & tail are not of importance to the several species.⁶ In the only two species which I have watched, the difference in flight & in the use of the tail was conspicuously great.⁷

The Duke who knows my orchis book so well might have learnt a lesson of caution from it, with respect to his doctrine of differences for mere variety or beauty.⁸ It may be confidently said that no tribe of plants presents such grotesque & beautiful differences which no one until lately conjectured were of any use; but now in almost every case, I have been able to shew their important service.

It should be remembered that with humming birds or orchids a modification in one part will cause correlated changes in other parts.⁹ I agree with what you say about beauty. I formerly thought a good deal on the subject & was led quite to repudiate the doctrine of beauty being created for beauty’s sake.¹⁰ I demur also to the Duke’s expression of “new births”:¹¹ that may be a very good theory but it is not mine,—unless indeed he calls a bird born with a beak $\frac{1}{100}$ ^th of an inch longer than usual “a new birth”; but this is not the sense in which the term w^d usually be understood.

The more I work the more I feel convinced that it is by the accumulation of such extremely slight variations that new species arise. I do not plead guilty to the Duke’s charge that I forget that natural selection means only the preservation of variations which independently arise.¹² I have expressed this in as strong language as I could use; but it w^d have been infinitely tedious had I on every occasion thus guarded myself. I will cry “peccavi”¹³ when I hear of the Duke or you attacking Breeders for saying that man has made his improved Shorthorns or Pouter-pigeons or Bantams. And I c^d quote still stronger expressions used by agricuturalists. Man does make his artificial breeds, for his selective power is of such importance relatively to that of the slight spontaneous variations. But no one will attack Breeders for using such expressions, & the rising generation will not blame me.¹⁴

Many thanks for your offer of sending me the Elements;¹⁵ I hope to read it all, but unfortunately reading makes my head whiz more than any thing else. I am able most days to work for 2 or 3 hours & this makes all the difference in my happiness.¹⁶ I have resolved not to be tempted astray, & to publish nothing till my Vol. on Variation is completed.¹⁷

You gave me excellent advice about the foot-notes in my Dog chapter,¹⁸ but their alteration gave me infinite trouble, & I often wished all the Dogs & I fear sometimes you yourself in the nether regions.

We (dictater & writer) send our best love to Lady Lyell¹⁹ | yours affectionately | Charles Darwin

If ever you sh^d. speak with the Duke on the subject please say how much interested I was with his Address & tell him about Sexual Selection.