Argumentation in business settings has gained renewed interest within social science re­search. Managers are seen as rhetors, and the spread of a practice depends on the discursive justifications used to rationalize it. These topics are particularly relevant for understand­ing the business leadership of one of the most famous merchants of the late Middle Ages: Francesco Datini, «The Merchant of Prato.» The merchant rhetor’s persuasive effort was practiced daily through his letters (not theorized) and became a cornerstone for building both a strong holding company and a trusted relationship with his partners. This case study provides a contribution to the history of Middle Ages merchants’ culture and to the impact of language in business activities.

Keywords: Medieval History, Medieval merchants, Argumentation, Francesco Datini.

Parole chiave: Storia medievale, Mercanti medievali, Argomentazione, Francesco Datini.