My dear Sir

You make a very great mistake when you speak of “the risk of your notes boring you”.¹ They are of the utmost value to me, & I am sure I shall never be tired of receiving them; but I must not be unreasonable. I shall give almost all the facts which you have mentioned in your two last notes, as well as in the previous ones;² & my only difficulty will be not to give too much & weary my readers. Your last note is especially valuable about Birds displaying the beautiful parts of their plumage. Audubon gives a good many facts about the antics of birds during courtship;³ but nothing nearly so much to the purpose as yours. I shall never be able to resist giving the whole substance of your last note.—⁴ It is quite a new light to me except with Peacock & Birds of Paradise: I must now look to Turkeys’ wings; but I do not think that their wings are beautiful when opened during courtship. Its tail is finely banded. How about Drake & Gallus bankiva?⁵ I forget how their wings look when expanded.— Your facts are all the more valuable, as I now clearly see that for Butterflies I must trust to analogy altogether in regard to sexual selection. But I think I shall make out a strong case (as far as the rather deceitful guide of analogy will serve) in the sexes of Butterflies being alike or differing greatly—in moths which do not display the lower surface of their wings not having them gaudily coloured &c &c.—nocturnal moths &c.—& in some male insects fighting for the females, & attracting them by music.—

My discussion on sexual selection, will be a curious one,—a mere dovetailing of information, derived from you, Bates, Wallace⁶ &c &c &c.— We remain at above address all this month & then return home. In the summer, could I persuade you to pay us a visit of a day or two & I w^d. try & get Bates & some others to come down.⁷ But my health is so precarious, I can ask no one, who will not allow me the privilege of a poor old invalid; for talking, I find by long & dear-bought experience trys my head more than anything, & I am utterly incapable of talking more than half-an-hour, except on rare occasions.—

Accept my cordial thanks for your extreme kindness & believe me my dear Sir | Yours sincerely | C. Darwin

I fear this note is very badly written, but I was very ill all yesterday & my hand shakes today.