My dear Sir

I have read your little essay with the greatest interest, & I thank you cordially for having taken such extraordinary trouble to oblige me.²

It tells me exactly what I especially wanted to know, & what I c^d not find out in any of the books which I possessed, namely, how far our knowledge at present extended, & where we were ignorant. I have not at present any thing more to ask, but yr kindness makes me think that if I have strong reason, you will allow me to trouble you once again. If you have spare time & sh^d feel inclined to come & sleep here on a Sunday night, I shall be delighted to see you; but I am bound to mention that I suffer from a strange state of weak health; which prevents me from talking long with any one, & I am liable to have bad days when I can hardly converse at all. I hope, in a week or two, that some of my sons will be at home, & then the house w^d not be so dull for you—³

With sincere thanks believe me | yours very truly | Charles Darwin

P.S. If you are able to come please do let me know, & I will inform you of the best route.