An erudite and popular librarian, Charles Edward Sayle (1864-1924) devoted his career to cataloguing and editing rare books in the University of Cambridge. His obituary praised him as 'a fine example of the type of man who likes to catalogue things in the right order'. This catalogue of incunabula and early printed books in the University Library was his most important project, taking over a decade to complete. Commissioned by the Library Syndicate in 1894, the catalogue was published in four volumes between 1900 and 1907. Even upon completion, Sayle's list was not final, as the rare book collections at the Library were undergoing a period of great expansion, having grown by a third during his cataloguing work, both through purchases and by donations or bequests. The first volume covers all books from 1475-1500, and books produced from 1501 to 1640 by the most important printers in London.