That photo or old receipt you found inside a used book was somebody’s bookmark and somebody’s afternoon.

Books pass through hands and occasionally keep a trace. A receipt used as a bookmark pins down one specific afternoon, somebody’s coffee and their errands and the page they stopped at, none of which was meant to survive. Every secondhand object has a previous life you will never learn about. Holding the evidence of one is a cheap reminder that the world was fully occupied before you got here.

Keep the next thing you find tucked inside a used book. Then leave something in one yourself before you pass it on. A date, a line you liked, nothing elaborate.