El Libro de Dos Columnas
I am the merchant's ledger with two columns. The first column is our own grain — grown in our fields, ground at our mill, sold at our stall. The second is the marketplace grain — brought by foreign merchants, displayed beside ours, a share paid to the crier who announced it. Both columns use the same abacus, the same scale, the same tariff. The customer sees one price. The merchant sees two margins. I am the double column that keeps the books honest.
A woman from Seville booked a trip for six. The scale priced her at the six-tier rate. Two days later, four more travellers joined. The group grew to ten — but the price snapped to the ten-tier, which was cheaper per head. The woman expected to pay more. Instead, the Steelyard slid: the surplus from the growth split forty to the compound, thirty to the organiser, and the rest returned to the group as an easing. A messenger brought her a refund she had not asked for. She wrote to the Scribe: 'Your mill counts backwards.' The Scribe replied: 'The mill counts fairly. The group's growth is the group's reward.' She booked three more trips that year. She never asked how the reckoning worked. She only trusted the number.