Über das Gedächtnis (English title: Memory: A Contribution to Experimental Psychology) by Hermann Ebbinghaus
Why would you want to read a book about the human memory that was published in 1885? As it turns out, Hermann Ebbinghaus' research has since been pretty much confirmed by modern-day researchers. Since I've seen his findings being quoted in other books, I wanted to go back to the source to check.
