Fable
City gate registration and footprints in the snow
Shuanghe City often snowed in winter, and at the city gate there was an old gatekeeper who specifically registered those entering and leaving. Who entered at what time, how many bags of goods they carried, and how many people accompanied them—he wrote it all in a thick ledger. The merchants found it troublesome, but once something was lost, the first thing they did was check the gatekeeper's ledger.
One early morning, the cloth shop discovered that three bolts of blue cloth were missing from the warehouse. The shopkeeper ran to the city gate to check the records, and the records were clear: last night twelve people entered the city, three left, and one was a porter carrying a large bundle. The time and package size were also noted beside the record. The shopkeeper pointed at the porter's name and said it must be him.
The porter protested his innocence, saying he had only gone to the south market to buy salt and had never gone near the cloth shop. It had just snowed in the city, so the night watchman followed the streets and alleys looking at footprints. On the snow there was a trail of small shoe prints, going from the cloth shop's back door around to the river, then turning back to West Lane, and finally stopping at the entrance of a dye works. The footprints were complete, but no one knew who had left them.
The gatekeeper's ledger could say who entered the city, but not which route he took inside. Footprints in the snow could piece together a path, but not whose footprints they were. The shopkeeper stared at names one moment and footprints the next, and the more he investigated, the more confused it became. He could not even be sure whose name to write as the victim and suspect when reporting the case, and no one could explain the mud spots on the vault door bolt.
The county clerk first thought of making the ledger thicker and having the gatekeeper write down more items: clothing color, package size, speaking accent. But after people entered the city they changed clothes, and the ledger still broke off at the city gate; everything afterward was guesswork. The night watchman then wanted to draw footprint maps of every street, marking even turns and stops, but without entry registration the maps still lacked people's names.
Later the city changed its method. At registration, the gatekeeper tied a small bronze tag to each parcel; the night watchman at the street corner recorded only the direction in which the tag passed, and warehouse entries and exits also recorded the tag number. When investigating a case, they first checked the ledger to confirm who had brought the tag into the city, then reconstructed the route from the records at each point, so that even who it was handed to midway and where it had stopped could be connected.
The blue cloth case was quickly solved: a dye-works employee borrowed someone else's coat, took a detour to move the cloth away, and by the river swapped the copper token onto an empty bundle. The ledger let people know which identity the responsibility fell on, and the records along the way let people know how the matter unfolded step by step. Without either side, the truth would have broken off halfway.