Complete the account of the contracts that carried long-distance trade.

In a commenda an investor supplied the capital and a travelling partner supplied the labour and the risk. A bill of exchange let a debt be settled in another city and another currency, moving value without moving coin. Italian cities adopted double-entry bookkeeping by the fourteenth century, which makes an error in the accounts detectable.

Each instrument solves a distinct problem, separating capital from risk, moving value safely, and detecting error at scale. Together they are what makes a firm possible: a merchant in Florence can be a partner in a voyage he never sees and know, from the books, whether it paid.