Here’s the full letter.

I am dying by inches, from not having any body to talk to about insects:—my only reason for writing, is to remove a heavy weight from my mind, so now you must understand, what you will perceive before you come to the end of this; that I am writing merely for my own pleasure & not your’s.

To answer the other commenter’s question: no. Darwin married first cousin Emma Wedgwood; this letter was to second cousin William Darwin Fox (“My dear Fox”).

If only Darwin had waited; he could’ve dropped bars with “I am dying by inches, from not having any body to talk to about finches.”