The vast output of Vivaldi is due primarily to the great demand placed upon him while employed at the Ospedal della Pieta, a foundling hospital for girls in Italy where Vivaldi was employed from as early as 1703 until about 1740. This unusual institution had been founded centuries before as a hospice for the countless unwanted girls born in Venice. Remarkably, it became one of Italy’s most prestigious musical institutions. Singers from around Europe would travel to hear the young girls with their technical perfection in singing and playing instruments.

Like Bach, Vivaldi composed out of need. Audiences were not interested in old works but wanted a consistent diet of new and fresh musical works. Composers were expected to produce or lose their positions. As chief composer and conductor for the concerts at the Pieta, Vivaldi, not surprisingly, turned out vast amounts of music, most of which calls for the highest sort of soloistic virtuosity. As new students were admitted, new works were needed for the weekly concerts given on all Sundays and holidays in a church were the girls were half-hidden behind a kind of openwork grille, their music floating out into the large open space where citizens and nobility of every sort crowded in attendance. Applause being forbidden in church, the audiences often showed their appreciation by stamping on the hard stone floor. After Vivaldi’s death in Vienna much of his work gathered in the corners of vast libraries. Only a few works held in Dresden survived World War I. An enormous amount of his work was held at Turin, and other libraries across Europe. It was only in the mid-twentieth century that interest developed in these older scores.