Sam Anderson in the NYT Magazine:
One day in college I was trawling the library for a good book to read when I found a book called “How to Read a Book.” I tried to read it, but must have been doing something wrong, because it struck me as old-fashioned and dull, and I could get through only a tiny chunk of it. That chunk, however, contained a statement that changed my reading life forever. The author argued that you didn’t truly own a book (spiritually, intellectually) until you had marked it up.
his hit home for me — it spoke to the little scribal monk who lives deep in the scriptorium of my soul — and I quickly adopted the habit of marginalia: underlining memorable lines, writing keywords in blank spaces, jotting important page numbers inside of back covers. It was addictive, and useful; I liked being able to glance back through, say, “Great Expectations,” and discovering all of its great sentences already cued up for me. (Chapter 4, underlined: “I remember Mr. Hubble as a tough high-shouldered stooping old man, of a sawdusty fragrance, with his legs extraordinarily wide apart: so that in my short days I always saw some miles of open country between them when I met him coming up the lane.”) This wasn’t exactly radical behavior — marking up books, I’m pretty sure, is one of the Seven Undying Cornerstones of Highly Effective College Studying. But it quickly began to feel, for me, like something more intense: a way to not just passively read but to fully enter a text, to collaborate with it, to mingle with an author on some kind of primary textual plane.
Soon my little habit progressed into a full-on dependency. My markings grew more elaborate — I made stars, circles, checks, brackets, parentheses, boxes, dots and lines (straight, curved and jagged). I noted intra- and extratextual references; I measured cadences with stress marks. Texts that really grabbed me got full-blown essays (sideways, upside-down, diagonal) in the margins. I basically destroyed my favorite books with the pure logorrheic force of my excitement, spraying them so densely with scribbled insight that the markings almost ceased to have meaning.