A borrowed book can return with evidence that another mind lived beside yours for a while.

A returned book carries traces. A folded corner, a pencilled line, a crumb, a passage marked where they stopped, and you can see where another mind slowed down. It is a small, unintended record of someone else’s attention running alongside yours through the same pages.

Lend books, and mark them lightly when you borrow if the owner would not mind. Ask what they underlined. It is one of the easier routes into a real conversation with someone about how they think.