Lecturer of Musicology, University of Michigan During the 1780s a cellist at the Opéra known only as Monsieur Hivart served as an agent for the opera-loving Russian nobleman Nicholas Sheremetev. Hivart\&##39;s letters to Sheremetev, preserved in the Russian State Historical Archive in St. Petersburg, contain valuable eyewitness accounts about how opera was staged in Paris. After briefly discussing Sheremetev\&##39;s activities as a patron of opera and his relations with Hivart, this paper will focus on what Hivart\&##39;s letters tell us about the first production of Salieri\&##39;s Les Danaïdes, one of the most successful French operas of the 1780s.