"And, lest the writing should perish with the writer and the work fail with the labourer, I leave parchment to continue this work, if perchance any man survive and any of the race of Adam escape this pestilence and carry on the work which I have begun . . ."
"Here, it seems, the author died."
See, Connie Willis' book Doomsday, available online at
http://vietmessenger.com/books/?cat=english&title=doomsdaybook&page=1
Or the BBC's article on the Black Death, especially
http://www.bbc.co.uk/history/british/middle_ages/black_01.shtml