My mother kept a running commentary in the margins of her cookbooks, and it is, without exaggeration, the most honest writing in our family's possession.

Next to a recipe for her mother-in-law's stew: "too much salt, always, don't tell her." Next to a recipe she'd clearly made a hundred times: "why do I keep writing this down, I know this by heart." The recipes themselves are almost incidental — instructions anyone could follow. The commentary is the actual inheritance.

the main text as alibi

I think the sidebar gets away with more because it can hide behind the pretense that it's not the point. The recipe is the point; the note is just a note. But take the notes out of my mother's cookbooks and you'd have a stranger's handwriting giving you instructions for someone else's dinner.

This is, I'd argue, true of most sidebars — footnotes, marginal notes, the small print, the aside. They claim to be secondary and then quietly become the only part worth keeping.^[1]

an inheritance you have to go looking for

Nobody hands you the margin. You have to go looking in it — flip past the recipe, notice the handwriting, decide it's worth reading. Maybe that's the last honest thing about it: it can't perform for you, because it was never expecting to be read by you at all.