This jar of keys is a family heirloom, handed down from grandfather to father to son. Most of the keys, as I understand the story, were to apartment doors and mailboxes. The family owned apartment buildings and when a tenant got locked out the landlord would come with this jar of keys and and try them, one at a time, until he found the right key. At some point family members tried to bring a little order to this chaos by numbering the keys but the system never caught on. Somewhere — in a door or a landfill — there are locks for each of these keys.