Re. writing notes in our books: Are you a Footprint Leaver or a Preservationist?
When I was in college, I took great joy in underlining and jotting notes in the margins of my books, but I don't really do that much anymore. Now (when I'm reading a book to review) I tend to take notes on a pad of paper and sometimes use little Post-it flags to mark particular words or lines.
While my college books were not disposable (I always planned to keep them all in my library), they were to some extent "working" copies. My highlighting and note-taking were part of my close reading of the texts and preparation for class discussions.