Charles Lamb (1775–1834) English essayist
Quoted in "Table Talk" http://books.google.com/books?id=LIxUAAAAcAAJ&q=%22greatest+pleasure+I+know+is+to+do+a+good+action+by+stealth+and+to+have+it+found+out+by+accident%22&pg=PA14#v=onepage in The Athenaeum magazine (4 January 1834).