this early period. In his old age Salieri hinted that these works were either purposely destroyed or had been lost, with the exception of a few works for the church. Among these sacred works there survives a Mass in C major written without a "Gloria" and in the antique a cappella style (presumably for one of the church's penitential seasons) and dated 2 August 1767. A complete opera composed in 1769 (presumably as a culminating study) La vestal (The Vestal Virgin) has also been lost. Beginning in 1766 Gassmann introduced Salieri to the daily chamber music performances held during Emperor Joseph II's evening meal. Salieri quickly impressed the Emperor, and Gassmann was instructed to bring his pupil as often as he wished. This was the beginning of a relationship between monarch and musician that lasted until Joseph's death in 1790. Salieri met Pietro Antonio Domenico Trapassi, better known as Metastasio, and Christoph Willibald Gluck during this period at the Sunday morning salons held at the home of the Martinez family. Metastasio had an apartment there and participated in the weekly gatherings. Over the next several years Metastasio gave Salieri informal instruction in prosody and the declamation of Italian poetry, and Gluck became an informal advisor, friend, and confidante. It was toward the end of this extended period of study that Gassmann was called away on a new opera commission and a gap in the theater's program allowed for Salieri to make his debut as a composer of a completely original opera buffa. Salieri's first full opera was composed during the winter and carnival season of 1770; Le Donne letterate and was based on Molière's Les Femmes Savantes (The Learned Ladies) with a libretto by , a dancer in the court ballet and a brother of the composer Luigi Boccherini. The modest success of this opera launched Salieri's 34-year operatic career as a composer of over 35 original dramas. Early Viennese period and operas (1770–1778) Following the modest success of , Le Donne literate Salieri received new commissions for writing two additional operas in 1770, both with libretti by Giovanni Boccherini. The first, a pastoral opera, L'amore innocente (Innocent Love), was a light-hearted comedy set in the Austrian mountains. The second was based on an episode from Miguel de Cervantes' Don Quixote – Don Chisciotte alle Nozze di Gamace (Don Quixote at the marriage of Camacho). In these first works, drawn