This monograph explores the impact of expanding long–distance communication networks on business, politics, diplomacy, international law, and personal freedom. Trailblazed initially by pedestrian and later also mounted couriers in the context of Italy, postal operations were first and foremost at the heart of the commercial revolution that transformed late medieval banking and commerce. In their next stage, they were also essential to the formation of centralized states and early modern diplomacy. Expanding access to postal services during the Renaissance was likewise instrumental to the inception of the Republic of Letters, while travel by the posts fostered personal mobility. The emergence of the earliest postal networks is therefore presented in this volume as the opening stage of an entire series of subsequent communications revolutions that ushered in the modern era.