Zaide, K344. By the end of the 1790s, Constanze Mozart had recovered from the emotional and financial shock of Wolfgang's death, and begun – with the help of a group of her late husband's associates – to bring order to his musical estate. Among the mass of unfinished works, sketches, and other unrealized projects she found a ‘German opera without a title, for the most part complete’. She and her helpers, unable to locate a libretto for it, even resorted to placing an advertisement in a widely read music journal (the Allgemeine musikalische Zeitung in Leipzig) asking any reader who recognized the characters in the drama to make contact with her. No one replied.

It took more than 150 years for Mozart scholarship to shed some light on the fragment, which includes sixteen musical numbers divided into two acts but lacks an overture and a finale. The piece was eventually given the name Zaide, after its main female figure. Like Die Entführung aus dem Serail, to which it bears more than a few similarities, Zaide is a singspiel in German; spoken texts are meant to advance the action between the musical numbers. In the score Constanze found (which is preserved today in the Staatsbibliothek Berlin) these spoken texts, except for cues, are missing. The challenge, then, is to find the source of the text Mozart and his librettist, the Mozart family friend Johann Andreas Schachtner, used to construct their version.