A Monteverdi Vespers in 1611

A letter from Lorenzo Campagna to Fabio Gonzaga dated 14 May 1611 mentions having heard new pieces of music for the Vespers composed by Monteverdi on the Feast of the Sensa (the Ascension), 12 May. The music he mentioned cannot have been the Vespro della Beata Vergine, which was only published in September 1610. He may however have heard the Respond, two psalms and Magnificat, shared by Marian Vespers and the Vespers for Ascension Day. The letter describes the week-long Mantuan Sensa celebration, the cavalcade of the Order of the Knights of the Redeemer, and identifies several distinguished personages, who were present at the service. The letter, which is here transcribed and translated in full, as well as reproduced in a facsimile, provides tantalizing but unspecific evidence of otherwise unknown sacred music written and performed by Monteverdi in Mantua