Here is a snippet:
An interesting slideshow, “The Past Between Two Covers,” accompanies the article online: http://www.nytimes.com/slideshow/2008/11/02/education/edlife/20081102RARE_SS_index.html.
[Robert] Darnton asks his students to “diagnose the symptoms” of a book—bits of petticoat in rag-based pages, symbols stamped in the binding, scribblings in the margins, called marginalia. By examining a book’s physical attributes, he says, “you can enter a world we have lost and understand it as it was.”
—“Handle This Book!” available from: http://www.nytimes.com/2008/11/02/education/edlife/rarebks.html