The metadata of a book extends beyond the keywords held between its
covers to the many hands the text has passed through; it's not enough
just to scan every page. We need to also scan the conversations, the
notes left in the margins, the stains from coffee, tea, and drink. We
need to eavesdrop on the readers, without whom every book is mute.
-- Mandy Brown. "On the library." A working library (6.18.09)
http://aworkinglibrary.com/library/archives/on_the_library/