This text constitutes one of the diplomatic manuals which began to be published in Europe in the mid-17th-18th centuries and theorized modern diplomatic pratice. Antoine Pecquet (1704-1762) was an officer in the Ministry of Foreign Affairs under Louis XV’s reign.
He published his essay in the line of the such manuals as Abraham de Wicquefort’s (1681) or François de Callières’ (1716) and seems to be the first author to formulate the concept of the corps diplomatique.
Source: KEENS-SOPER Maurice, “François de Callières and Diplomatic Theory”, in The Historical Journal, vol.16, n°3 (1973), Cambridge University Press, pp. 485-508. Accessible online on JSTOR through the Library’s database gateway.