My dear Sir

I thank you warmly for your letter.¹ I did not in the least know that you had attended to my work. I assure you that the attention which you have paid to it, considering your knowledge and the philosophical tone of your mind (for I well remember one remarkable letter you wrote to me, and have looked through your various publications) I consider one of the highest perhaps the very highest compliment which I have received—² I live so solitary a life that I often do not hear what goes on, and I should much like to know in what work you have published some remarks on my book.³   I take a deep interest in the subject and I hope not simply an egotistical interest; so therefore you may believe how much your letter has gratified me; I am perfectly contented if anyone will fairly consider the subject whether or not he fully or only very slightly agrees with me.

Pray do not think that I feel the least surprise at your demurring to a ready acceptance; in fact I should not much respect anyone’s judgment who did so   that is if I may judge others from the long time which it has taken me to go round. Each stage of belief cost me years. The difficulties are as you say many & very great: but the more I reflect the more they seem to me to be due to our underestimating our ignorance.   I belong so much to old times that I find that I weigh the difficulties from the imperfection of the geological record, heavier than some of the younger men.— I find to my astonishment and joy that such good men as Ramsay, Jukes Geikie and one old worker Lyell do not think that I have in the least exaggerated the imperfection of the record.⁴ If my views ever are proved true our current Geological views will have to be considerably modified—

My greatest trouble is not being able to weigh the direct effects of the long continued action of changed conditions of life without any selection, with the action of selection on mere accidental (so to speak) variability— I oscillate much on this head but generally return to my belief that the direct action of the conditions of life has not been great.   At least this direct action can have played an extremely small part in producing all the numberless and beautiful adaptations in every living creature.

With respect to persons belief, what does rather surprise me is that anyone (like Carpenter) should be willing to go so very far as to believe that all Birds may have descended from one parent, and not go a little farther and include all the members of the same great Division;⁵ for on such a scale of Belief, all the facts in Morphology and in Embryology (the most important in my opinion of all subjects) become mere Divine Mockeries. This leads me to remark how singularly few have judged the argument on right principles   many complain that I have not proved that any one species changes into another and they ignore the fact that the view given, apparently groups together and explains many phenomena. No one urges as a fatal objection to the Theory of Light that the undulations in the ether cannot be proved—or the very existence of ether, yet because the undulatory theory explains much it is now universally admitted—

I cannot express how profoundly glad I am that some day you will publish your theoretical view on the modification & endurance of Brachiopodous species;⁶ I am sure it will be a most valuable contribution to knowledge.— My weak health interferes much with my work, but I am never idle— I should never, however, be able to acquire sufficient knowledge to trace and appreciate the changes in any great group of beings, as you will be able to do with Brachiopods.   I am at present at work on “Variation under Domestication” and slow and laborious work I find it, but I think it will throw some little light on the laws of variation— Have you read Hooker’s Introduction to the Flora of Australia;⁷ I think it would interest you?

Pray forgive this very egotistical letter, but you yourself are partly to blame, from having pleased me so much. I have told Murray to send a copy of new Edit to you and have written your name.—⁸

With cordial thanks. | Pray believe me | My dear Sir. | Yours very sincerely | Ch Darwin

As my Copyist writes so well, I do not apologise for length of this

There is only a little added & a little modified in Ch IX & X of new Edition of Origin.—