Do you understand the difference?”

“I think so,” she said.

And she slid the little laminated card carefully into the front pocket of her purple backpack, in beside the star patches, where she would carry it for a long time.

Outside, the warm Florida air met us all at once — sunshine, and palm trees, and the hum of airport traffic, and that particular soft smell of summer that tells your body you have arrived somewhere.

My sister was waiting near the curb, and when she saw us she waved both arms over her head, wildly, extravagantly, as though we were coming home from some long and dangerous voyage.

And in a way, I suppose we were.