The Case for Marginalia

Librarians spend a fair amount of energy erasing marginalia. Understandably — a used copy full of someone else's underlining is, for most buyers, a defect. But the scholars who study great annotators (Coleridge filled other people's books with essay-length arguments in the margins; Twain treated blank space as an invitation) tend to agree on something: the note written in the heat of reading, before the argument has had time to cool into a review, is often truer than anything written after the book is closed.

A highlight without a comment is just a bookmark with extra steps. What makes marginalia worth keeping is the half-formed reaction next to it — wait, didn't she just contradict herself two chapters ago — the kind of thought that gets smoothed away by the time you'd write a proper review.

The obvious problem with marginalia has always been that it's trapped in one copy of one book. Yours. Nobody else's underlining shows up in your copy, and yours never reaches theirs. Which is, when you think about it, a strange thing to have accepted for so long about a habit that's fundamentally social — arguing with a text is rarely a private act, it just used to be an isolated one.

Give marginalia a thread instead of a margin, and it stops being a private habit and starts being closer to what annotation was always halfway trying to be: a conversation with everyone who stopped at the same sentence and had a reaction worth keeping.