This opera was first performed at the Burgtheater, St. Michael’s Square Vienna, which later became the “K.K. Hoftheater nächst der Burg”, on the 26th of January 1790, the day before Mozart’s 34th birthday and only two years before his death. It was well received, and ten performances were given in that year.
Mozart, accompanied by his father, had spent two years in Italy when he was 15 years old, but it was Opera Buffa not Seria for which he was famed, and “Cosi” is definitely Buffa.
The main role of the overture was to provide a foretaste of what to expect. Another purpose of the overture, in an era when the public, although appreciative of Mozart’s music, was not as reverential as we are today, was to permit latecomers an opportunity to take their seats. “Come on, they’re playing the overture!”
The piece is in the key of C major, beginning with a fourteen bar slow introduction. This is a common musical form; a kind of “get ready” for the rhythmic hushed Presto with its alternating themes, which give the work both urgency and a sense of mystery.