Darwin enthusiasts, fans of the history of science, and retired secret policemen will all enjoy rifling through the treasures of the Darwin Correspondence Project, which was first set up in 1974 by science historian the late Frederick Burkhardt as an attempt to locate and publish summaries of all letters written by Charles Darwin. To date, the Project has located more than 15,000 letters sent to or written by Darwin over more than 60 years of his life.
The project has moved online, to great effect. Thematic sections dive into topics like “Darwin & Science”, and present letters tied to those themes and their sub-themes — and including, for at least two of them, a very useful “Top 10 letters” page that identifies and explains the most important and influential items of correspondence. Each letter is prefaced by a point-form summary, the text of the letter itself, and cross-references to people and places mentioned. For targeted research it is a remarkable resource, yet unguided dives into the broader sea of missives will often yield pearls; the second letter I happened to click on (sent by Darwin only 6 months before sailing with the HMS Beagle, and two months before he even knew he would be assigned to the ship as its naturalist) contained this prophetic rumination:
I have been working at so many things: that I have not got on much with Geology: I suspect, the first expedition I take, clinometer & hammer in hand, will send me back very little wiser & good deal more puzzled than when I started.— As yet I have only indulged in hypotheses; but they are such powerful ones, that I suppose, if they were put into action but for one day, the world would come to an end…
— Extract from a letter to Cambridge botany professor John Stevens Henslow, 11 July 1831