Think back over the chapters. In the middle of the night, a homesick cricket dreams of the greenest leaf in Connecticut — and wakes with half of the family’s rarest bill inside him. He could vanish between the bars before morning; instead he folds his wings and waits for the judge. Across the station, a mouse who has counted his coins a thousand times counts them once more — and pushes two dollars of his two-ninety-three across the floor toward a friend he has known for barely a week. By sunrise there is a tower of silver on the shelf, and nobody upstairs will ever know who built it.

The dollar bill in your pocket is not really paper at all. American money is printed on a special blend of cotton and linen — cloth, not wood — because cloth is far more durable than ordinary paper. A bill must survive being folded, crumpled, sat on, and soaked, thousands of times over. Even so, money wears out. A one-dollar bill lasts only a few years as it passes from hand to hand and store to store — what banks call staying in circulation — before it grows too limp and torn to use.

Worn-out bills are collected by banks, shredded, and replaced with crisp new ones. And a damaged bill is not always a lost cause: the government’s rule is generous, and if you can turn in clearly more than half of a torn bill, you can redeem it — exchange it for a whole new one. So a bill nibbled at the edges is only wounded. Rarer notes, such as the two-dollar bill that most cash drawers hold only one of, are certainly worth the walk to the bank. But if half of a bill has vanished completely — say, into a sleeping cricket — its owner has a real problem.

No right or wrong — close the screen and tell someone nearby what happened in this part. Can’t find anyone? Tell yourself out loud. The moment you teach it, you truly understand it.