Dr Falk Eisermann is head of the Incunabula Division at the Staatsbibliothek zu Berlin and is considered a world expert in the field. He also heads the Gesamtkatalog der Wiegendrucke (Union catalogue of incunabula), GW for short. Founded in 1904 it's objective is to list all 15th-century items printed from movable type. Today the job is reportedly about fifty percent complete. Lots of work remains. 

I met with Falk in his green-carpeted office at the Staatsbibliothek in Berlin to talk about his role as a rare books librarian, about incunabula, and about his quest to find and catalogue it all.