My dear Lyell, I thank you for your very interesting letter. I have the true English instinctive reverence for rank, and therefore liked to hear about the Princess Royal. ("I had...an animated conversation on Darwinism with the Princess Royal, who is a worthy daughter of her father, in the reading of good books, and thinking of what she reads. She was very much au fait at the 'Origin,' and Huxley's book, the 'Antiquity,' etc."--(Lyell's 'Life,' vol. ii. page 385.) You ask what I think of the Duke's address, and Ishall be glad to tell you. It seems to me EXTREMELY clever, like everything 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 (page 93, 3rd edition) on beautiful plumage being acquired through SEXUAL selection. The duke may think this insufficient, but that is another question. All analogy makes me quite disagree with the Duke that the difference in the beak, wing and tail, are not of importance to the several species. In the only two species which I have watched, the difference in flight and in the use of the tail was conspicuously great.
The Duke, who knows my Orchid book so well, might have learnt a lesson of caution from it, with respect to his doctrine of differences for mere variety or beauty. It may be confidently said that no tribe of plants presents such grotesque and beautiful differences, which no one until lately, conjectured were of any use; but now in almost every case I have been able to show 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. I agree with what you say about beauty.
I formerly thought a good deal on the subject, and was led quite to repudiate the doctrine of beauty being created for beauty's sake. I demur also to the Duke's expression of "new births." That may be a very good theory, but it is not mine, unless indeed he calls a bird born with a beak 1/100th of an inch longer than usual "a new birth;" but this is not the sense in which the term would 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. ("Strictly speaking, therefore, Mr. Darwin's theory is not a theory on the Origin of Species at all, but only a theory on the causes which lead to the relative success and failure of such new forms as may be born into the world."--"Scotsman", December 6, 1864.) I have expressed this in as strong language as I could use, but it would have been infinitely tedious had I on every occasion thus guarded myself. I will cry "peccavi" 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 could quote still stronger expressions used by agriculturists. 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, and the rising generation will not blame me.
Many thanks for your offer of sending me the 'Elements.' (Sixth edition in one volume.) I hope to read it all, but unfortunately reading makes my head whiz more than anything else. I am able most days to work for two or three hours, and this makes all the difference in my happiness. I have resolved not to be tempted astray, and to publish nothing till my volume on Variation is completed. You gave me excellent advice about the footnotes in my Dog chapter, but their alteration gave me infinite trouble, and Ioften wished all the dogs, and I fear sometimes you yourself, in the nether regions.
We (dictator and writer) send our best love to Lady Lyell.
Yours affectionately, CHARLES DARWIN.
P.S.--If ever you should speak with the Duke on the subject, please say how much interested I was with his address.
[In his autobiographical sketch my father has remarked that owing to certain early memories he felt the honour of being elected to the Royal and Royal Medical Societies of Edinburgh "more than any similar honour." The following extract from a letter to Sir Joseph Hooker refers to his election to the former of these societies. The latter part of the extract refers to the Berlin Academy, to which he was elected in 1878:--"Here is a really curious thing, considering that Brewster is President and Balfour Secretary. I have been elected Honorary Member of the Royal Society of Edinburgh. And this leads me to a third question. Does the Berlin Academy of Sciences send their Proceedings to Honorary Members? Iwant to know, to ascertain whether I am a member; I suppose not, for Ithink it would have made some impression on me; yet I distinctly remember receiving some diploma signed by Ehrenberg. I have been so careless; Ihave lost several diplomas, and now I want to know what Societies I belong to, as I observe every [one] tacks their titles to their names in the catalogue of the Royal Soc."]
CHARLES DARWIN TO C. LYELL.
Down, February 21 [1865].
My dear Lyell, I have taken a long time to thank you very much for your present of the 'Elements.'
I am going through it all, reading what is new, and what I have forgotten, and this is a good deal.
I am simply astonished at the amount of labour, knowledge, and clear thought condensed in this work. The whole strikes me as something quite grand. I have been particularly interested by your account of Heer's work and your discussion on the Atlantic Continent. I am particularly delighted at the view which you take on this subject; for I have long thought Forbes did an ill service in so freely making continents.