On today's date in 1773, Wolfgang Mozart was a few days shy of his seventeenth birthday and found himself in Italy, in the company of his father, Leopold. This was their third trip to Italy, in fact, and this time around young Wolfgang was under contract to produce a new opera, "Lucio Silla," for the city of Milan. The lead singer scheduled for Mozart's new opera was the castrato Venanzio Rauzzini, a male soprano, who, Leopold Mozart said 'sang like an angel." For Rauzzini, the teenage Mozart also composed a sacred work, tailor-made to show off his remarkable voice and vocal dexterity: this was a solo motet entitled "Exsultate, jubilate," which had its premiere performance in Milan's Church of San Antonio on today's date in 1773. The church is still standing, but these days the authentic performance practice movement hasn't gone quite so far as to surgically create new male sopranos, so more often than not, Mozart's "Esultate jubilate" is sung by sopranos or mezzos, who adjust portions of the vocal line up or down to make the best effect in the work's more brilliant passages. And so, although originally written for a divo, "Esultate, jubiliate" is one of the earliest of Mozart's major works to find a lasting place in the repertory of many grateful divas.