Dear & much respected Sir

I ought to apologise for troubling you; but I have at last carefully read your excellent criticisms on my Book.—¹ I agree with much of them, & wholly with your final sentence.² The objections & difficulties, which may be urged against my view, are indeed heavy enough almost to break my back; but it is not yet broken! You put very well & very fairly that I can in no one instance explain the course of modification in any particular instance. I could make some sort of answer to your case of the two Rats;³ & might I not turn round, & ask him, who believes in the separate creation of each species, why one Rat has a longer tail or shorter ears than another? I presume that most people would say that these characters were of some use or stood in some connection with other parts; & if so, natural selection could act on them. But as you put the case, it tells well against me. You argue most justly against my question, whether the many species were created as eggs or as mature &c;⁴ I certainly had no right to ask that question.—

I fully agree that there might have been as well 100,000 creations as 8 or 10, or only one. But then on the view of 8 or 10 creations, (i.e. as many as there are distinct types of structure) we can on my view understand the homological & embryological resemblances of all the organisms of each type; & on this ground almost alone I disbelieve in the innumerable acts of creation.—   There are only two points on which, I think, you have misunderstood me: I refer only to one Glacial period as affecting the distribution of organic beings: I did not wish even to allude to the doubtful evidence of Glacial action in the Permian & Carboniferous periods.⁵ Secondly, I do not believe that the process of development has always been carried on at the same rate in all different parts of the world.⁶ Australia is opposed to such belief.— The nearly contemporaneous equal development in past periods I attribute to the slow migration of the higher & more dominant forms over the whole world; & not to independent acts of development in different parts.—   Lastly, permit me to add that I cannot see the force of your objection, that nothing is effected until the origin of life is explained:⁷ surely it is worth while to attempt to follow out the action of Electricity, though we know not what electricity is.

If you should at any time do me the favour of writing to me, I should be very much obliged if you would inform me, whether you have yourself examined Brehm’s sub-species of Birds;⁸ for I have looked through some of his writings, but have never met an Ornithologist who believed in his w⁠⟨⁠orks.⁠⟩⁠ Are these sub-species really characteristic of certain different regions of Germany?

Should you write, I should much like to hear how the German Edition sells.—

With my once more sincerely expressed gratitude & with entire respect | I beg leave to remain | Dear & Honoured Sir | Yours sincerely & respectfully | Charles Darwin