"'It befits a merchant,' wrote Leon Battista Alberti, the great architect who belonged to one of the chief trading-companies of Florence, 'always to have ink-stained hands.' Datini was of the same opinion. While the heads of some firms left much of their correspondence to their fattori, he insisted, even in his old age, on writing every letter with his own hand--
'I wish to look over each of my papers,' he wrote in 1399, 'and set them in order and mark them, that I may be clear about each man with whom I have to do.'
What did all these letters look like, and how did they reach their destination? They were written on sheets of paper folded in three, closed by a small cord passing through holes in the edges, and sealing it at each end. The side containing the address was marked with the same trade-mark which was also placed on Francesco's bales of merchandise. Each bundle of letters was then wrapped in a water-proof canvas and enclosed in a bag or purse called a scarsella, sealed by the merchant and worn at the messenger's belt."
The Merchant of Prato Iris Origo