My dear Sir

I am much obliged for your letter of Oct. 10^th. from Celebes received a few days ago:² in a laborious undertaking sympathy is a valuable & real encouragement. By your letter & even still more by your paper in Annals, a year or more ago,³ I can plainly see that we have thought much alike & to a certain extent have come to similar conclusions. In regard to the Paper in Annals, I agree to the truth of almost every word of your paper; & I daresay that you will agree with me that it is very rare to find oneself agreeing pretty closely with any theoretical paper; for it is lamentable how each man draws his own different conclusions from the very same fact.—

This summer will make the 20^th year (!) since I opened my first-note-book, on the question how & in what way do species & varieties differ from each other.— I am now preparing my work for publication, but I find the subject so very large, that though I have written many chapters, I do not suppose I shall go to press for two years.—⁴

I have never heard how long you intend staying in the Malay archipelago; I wish I might profit by the publication of your Travels there before my work appears, for no doubt you will reap a large harvest of facts.—⁵ I have acted already in accordance with your advice of keeping domestic varieties & those appearing in a state of nature, distinct; but I have sometimes doubted of the wisdom of this, & therefore I am glad to be backed by your opinion.— I must confess, however, I rather doubt the truth of the now very prevalent doctrine of all our domestic animals having descended from several wild stocks; though I do not doubt that it is so in some cases.— I think there is rather better evidence on the sterility of Hybrid animals that you seem to admit: & in regard to Plants the collection of carefully recorded facts by Kölreuter & Gærtner, (& Herbert) is enormous.—⁶

I most entirely agree with you on the little effects of “climatal conditions”, which one sees referred to ad nauseam in all Books; I suppose some very little effect must be attributed to such influences, but I fully believe that they are very slight.—⁷ It is really impossible to explain my views in the compass of a letter on the causes & means of variation in a state of nature; but I have slowly adopted a distinct & tangible idea.— Whether true or false others must judge; for the firmest conviction of the truth of a doctrine by its author, seems, alas, not to be slightest guarantee of truth.—

I have been rather disappointed at my results in the Poultry line; but if you sh^d. after receiving this stumble on any curious domestic breed, I sh^d be very glad to have it;⁸ but I can plainly see that this result will not be at all worth the trouble which I have taken.— The case is different with the domestic Pigeons; from its study I have learned much.— The Rajah has sent me some of his Pigeons & Fowls & Cats skins from interior of Borneo, & from Singapore.—⁹

Can you tell me positively that Black Jaguars or Leopards are believed generally or always to pair with Black?¹⁰ I do not think colour of offspring good evidence.— Is the case of parrots fed on fat of fish turning colour, mentioned in your Travels?¹¹ I remember case of Parrot with, (I think,) poison from some Toad put into hollow whence primaries had been removed.

One of the subjects on which I have been experimentising & which cost me much trouble, is the means of distribution of all organic beings found on oceanic islands; & any facts on this subject would be most gratefully received: Land-Molluscs are a great perplexity to me.—

This is a very dull letter, but I am a good deal out of health; & am writing this, not from my home, as dated, but from a water-cure establishment.

With most sincere good wishes for your success in every way I remain | My dear Sir | Yours sincerely | Ch. Darwin