To B. D. Walsh   13 April [1868]

My dear Sir

It was extremely kind of you after being ill & overworked with your Report to take so much trouble in looking through your collection & writing me such copious & minute notes.¹ I value your information much, as I well know that you are so trustworthy. Not only are many of the facts, which you communicate, very interesting to me; but the negative evidence is of much value, for I was very doubtful how far I could trust the information, which I picked up from various Books & papers. Many of the English entomologists, however, have been most kind in assisting me in various ways.² I have found my present subject of Sexual Selection very perplexing, & I must leave a multitude of points doubtful, & can seldom judge except by analogy. But I must make the best of a rather bad job.—

I hope that you will soon receive or have received my new Book, which I have lately heard, is to be republished in the U. States.—³ It is much too large a book, but if I had to do it again, I hardly know what I ought to strike out.— I see by the heading of your letter that you still retain your Editorship, which I fear you must find very hard work.—⁴

With cordial thanks, My dear Sir | Yours sincerely | C. Darwin

I have just read again your letter & it really is a mine of wealth to me.—