To what extent did secrecy emerge as the uncontested norm for international negotiations after the Renaissance? This article introduces six key negotiation practitioners from 17th century Europe, including some of the earliest writers on negotiation: Hotman, Mazarini, Wicquefort, Rousseau de Chamoy, Callières, and Pecquet. An analysis of their writings demonstrates that if an ambassador had to appear in the bright light of the royal court, he became constantly preoccupied by secrecy. He needed to find ways to protect his own secrets from third parties and uncover the secrets of others. These concerns from earlier times helped to establish secrecy as the paradigm for modern negotiation.