Anyone who is familiar with the other psalms and the Magnificat from the 1739 cycle, as well as with the concertos written the following year for the Prince of Saxony’s visit, won’t find anything particularly unusual in this Nisi Dominus. This is galant rather than contrapuntal Vivaldi. But his use of three solo voices (one soprano and two contraltos) without choir, and of an assortment of no less than five instruments (viola d’amore, tenor chalumeau, violin in tromba marina, cello and organ) gives the piece a brilliance and a virtuoso character that are unparalleled elsewhere in Vivaldi’s work, except of course in the oratorio Juditha triumphans.

It’s striking that Vivaldi wrote arias accompanied by the chalumeau and the viola d’amore in 1739, as he had not used these instruments in a sacred vocal context since Juditha in 1716. How would you explain this unusual aspect of the Nisi Dominus as compared to the much more sober scoring of the Magnificat, the Lauda Jerusalem and the Beatus vir, which date from the same period?

That’s a very pertinent question. When the maestri di cappella of the Ospedale della Pietà made up a cycle of four to six psalms in order to renew their repertoire, they sought variety above all. They required works for single and double choirs, works with a single movement, multiple-movement works, works with and without choir, and with or without obligato instruments…in a word, the purpose of the new Nisi Dominus was to provide exactly what the other works did not provide, which explains its originality.

What about the scores that were discovered in Berkeley Castle, in England? How did the opportunity arise for you to study these new documents?

Once again I benefited from the cooperative spirit that always (or nearly always!) prevails among musicologists. The archivist at Berkeley Castle, which is not far from Bristol, discovered a manuscript containing fifty pieces (an overture, five cantatas, and 44 arias, to be precise). He noticed that the only name on the frontispiece was Giovanni Porta’s. He checked in New Grove, and learned that Faun Tiedge Tanenbaum had written the article on Porta. He contacted her, she contacted me, and the musicological wheels slowly began to turn.

Where do you think the collection came from?

It appears to have belonged to a British tourist – unfortunately unknown – who was in Venice during the winter of 1716-1717.

Vivaldi is represented in the collection by several arias from his third Venetian opera, La costanza trionfante (1716). The score has been lost, but certain arias are now housed in Berlin, Copenhagen, Paris and Skara. How many previously unknown arias are in the Berkeley manuscript?

The collection includes eight arias from La costanza trionfante, six of them previously unknown. The other arias are mainly by Lotti (from Polidaro, Foca superbo and Alessandro severo), Porta (from La costanza combattuta in amore) and Pollarolo (from Ariodante).