My dear Hooker

I was pleased to get your Dublin note with all your vivid recollections of Oxford.² How I sh^d. have liked to have heard with you that anthem out of the Messiah!

I return A. Grays capital, first-rate criticism on Buckle, whom I have not nearly finished: I am sorry to say it is not my copy but Mudies:³ if I had known how much I sh^d. have been interested in it, I would have bought it.— I also send a note from A. Gray to me, which you need not return; as I sh^d. like you to see what he says on our disputed point.—⁴ But do not think I shall lay too much stress on it. I have almost finished my discussion; but it will take some little time to have have it copied; & as my health has been lately wretched, I start in 9 days for a fortnight of Hydropathy & rest.⁵ On my return I will send it, & most grateful I am to you being willing to take the trouble to read it. I enclose a memorandum on way which I want you to consider my M.S. which please keep & read, when I send the M.S.—⁶ By the way you will see in A. Gray’s note, how preciously too high he estimates the probable value of my work.

I am extremely interested at what you say about the Cape animals being the same with European species during Glacial epoch: it is just like what I fancy has happened in case of Brazil in regard to Cordillera mammals.— The more I think of Glacial epoch, the more inclined I am to view it as an immense geological epoch, which we vastly underrate because our northern species in migrating in a body N. to S. & then S. to N. did not become changed, whereas, the very same species & other bodies of species, where placed amidst interlopers did become modified.⁷ I suspect the rate of organic change in any one country, will prove a very poor measure of time.

Livingstones work is very interesting in regard to the Cape, I think, as showing that it is separated from N. Africa by no very high land.⁸ The whole must have been continuous land from before the glacial epoch, (allowing animals during that epoch to migrate) for the sea shells are so different on E & W. coasts. But before the Cape region was united to N. Africa, the Cape must have been, I sh^d. think a large group of islands, with no mammifers; for otherwise, they would not have had such a N. hemisphere character.— Why I go on speculating this way I know not. So farewell.—

Thank God I have nearly done my odious & wearisome discussion on big & small genera, which has almost killed me.

Adios | Yours Most truly | C. Darwin

I shall not be in London in time enough to see Falconer;⁹ though I shall be there for an hour or two on the 15^th to meet Miller to get wisdom on the geometry of Bees cells,—a subject which has interested me intensely, as the most difficult of all instincts to comprehend by my theory.¹⁰