Die Schuldigkeit Dies Ersten Gebots K 35

This work, possibly commissioned by Prince-Bishop Sigismund Christoph von Schrattenbach , was assigned to three Salzburg composers: W. A. Mozart (part 1), Michael Haydn (part 2), and Anton Cajetan Adlgasser (part 3). Only the manuscript of part 1 has survived. Here Mozart drew heavily on the Salzburg tradition of church music and school dramas, perhaps taking Johann Ernst Eberlin and even his father Leopold as his models.

The first performance took place in the Knights’ Hall of the prince’s palace on 12 March 1767. The libretto was supplied by Ignaz Anton Weiser (1701–1785), town councillor and mayor of Salzburg.

Mozart wrote out many of theappoggiaturas in this early work, thereby providing a useful guide to the vocal practices of his day. Aria No.2 has come down to us with an instructive passage in which the Vocal part is ornamented in the hand of Leopold Mozart.