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