Marginalia, strictly, means notes written in the margin of a text — but the word has come to cover a much wider habit than the pencil marks most people picture. Early readers used margins as a second document running alongside the first: corrections, cross-references to other books, arguments with the author, sometimes whole essays that outgrew the space and spilled onto pasted-in slips of paper.
Coleridge is the usual reference point — his marginalia were collected and published as books in their own right, several volumes of them, because the notes were often better than what he was annotating. But the habit is older and more ordinary than that. Medieval manuscripts are full of it: scribes complaining about the cold, readers doodling in the corners, one famous note that just says ‘new parchment, bad ink, I am not happy.’
What interests me about the habit isn’t the wit of the good examples. It’s the structural fact that a margin is a place where reading turns into writing without any ceremony about it. You don’t have to decide to start a project. You just write next to the sentence that provoked you, and the provocation and the response stay physically attached to each other for as long as the book exists.
This site borrows its name and its shape from that habit more than from the blog form it technically is. The cadence calendar below the essays exists because a commonplace book always had a spine you could feel the thickness of — you knew roughly how much you’d written this year just by picking it up. A blog with a reverse-chronological list doesn’t give you that feeling back. The calendar is an attempt to.