To J. D. Dana   30 December [1859]

My dear Mr. Dana,

I am most truly & deeply grieved at the news in your letter.¹ God grant that you may soon recover. When I think of the amount of labour which you have undergone my only wonder is that you have not broken down sooner. But one often hears of a year’s rest completely restoring the power of the brain.— Most regular medical men sneer at the Water-cure (I do not at all know whether it is adopted in the U. States) but I have tried it repeatedly & always with wonderfully good effects, but not permanent in my case. When I first tried it, I could not sleep & whatever I did in the day haunted me at night with vivid & most wearing repetition.² The W. cure at once relieved this. It makes the skin act so vigorously that all other organs get a rest. For years I have been in your state, that an hour’s conversation worked me up to that degree that I wished myself dead. But then my head never ultimately suffers; for my peccant part is the stomach & fatigue of any kind always brings on great derangement & ultimately severe vomiting. So that the weak organ seems to save the more important one.— If you come to England I hope you will spare us a week & you need not fear being fatigued here; as I believe I should have to cry, “hold, enough” even before you would.—

You must not think of reading my book for a long time, as my friends tell me it is tough reading.³ It has been far more successful than I even dreamed of & has made some few first rate converts; but has been bitterly attacked. The difficulties are so great that I wonder I have made any converts, though of course I believe in truth of my own dogmas. Most sincerely for your own sake & for that of Natural Science do I hope for your speedy & entire recovery.

Believe me | Yours most truly | C. Darwin.