An ordinary doorway can mark the edge of a much larger private world.

Every front door on a street is the entrance to something you know nothing about. From outside it is a rectangle with a number on it; from inside it is a whole climate of habits, arguments, jokes, illnesses, and small rules nobody else has ever heard. The ordinariness of the outside is not a clue to the scale of the inside. This is roughly the situation with people as well.

Walk down a familiar road and let yourself register that each door is a world. Then extend the same assumption to the next person who is brief with you.