Merchants’ marks were used initially as a tool of commerce, on consignments of goods, in the Middle Ages. In the sixteenth century, however, they became more like a coat of arms for people who didn’t have one – a form of professional identity. Medieval manuscripts also feature the marks used in this way, and Thomas Kittel (DPhil student, English Literature) argues that this is interesting because it shows us how medieval people understood their identity and how books (such as The Canterbury Tales) functioned in social exchanges.