We often think of Haydn as a composer of symphonies, string quartets and piano sonatas – that is, of instrumental music in various forms. But in fact, he probably wrote as much vocal music, in a variety of genres. The late, great oratorios are still justly famous – The Creation and The Seasons – but he also composed twelve large-scale Masses, a number of cantatas and other sacred works, as well as songs, concert arias and as many as 21 operas and Singspiele. Some of these have been lost, but the majority still exist in more or less complete form. The earliest of these is Acide, the fragment of an opera composed for the celebrations of the wedding of Count Anton Esterházy and Countess Maria Theresia Erdödy, and performed at the Esterházy residence at Eisenstadt on 11th January 1763.