How a grain loan could grow beyond the harvest
A loan of grain did not have to be repaid as the same amount. A lender could require interest: an additional share owed for the use of what had been borrowed. With compound interest, unpaid interest is added to the debt, so later interest is calculated on a larger balance. A debt can therefore grow even when the borrower takes out no new loan.
In an agricultural economy, that arithmetic had practical consequences. Grain was both food and a store of value, and harvests arrived on a seasonal schedule. A written record could preserve how much had been lent, what repayment was due, and how an obligation changed over time—details that memory alone could not reliably settle.
Records made obligations calculable
The important shift was not that a tablet made debt fair or easy to repay. It made the terms countable. Once quantities and dates could be recorded, lenders and borrowers could compare what was delivered with what was owed, while officials could keep track of stores and claims. Accounting turned a personal obligation into something that could persist beyond a single conversation or season.
That kind of calculation belonged to the same world as transport, but it did not depend on wheeled carts. Before moving goods farther or faster could transform trade, communities already faced a different logistical problem: keeping track of what had been stored, borrowed, and promised. The debt’s growth could be set in motion by arithmetic alone.
