The Metropolitan Police

Always carry a little book with you, and preserve it with great care, said Leonardo da Vinci

In 1299, Amatino Manucci, a Florentine helping to run a merchant’s business in Provence, kept at least seven ledgers and notebooks, each serving a specific purpose. One covered the firm’s trade in wool and cloth, another in wheat, barley and other victuals, and so on. It wasn’t just figures Manucci worked with. It was also financial concepts, quite advanced by the standards of that time: accounting entities and periods, profit and depreciation – notions that heralded the invention of accounting as we know it. ‘If you’ve ever tapped numbers into an Excel grid,’ Roland Allen writes in his engaging popular history, ‘you have Manucci and his contemporaries to thank –