Johann Mattheson was a German composer, singer, writer, lexicographer, diplomat and music theorist. He was a close friend of George Frideric Handel, although he nearly killed him in a sudden quarrel, during a performance of Mattheson’s opera Cleopatra in 1704. The bulk of his compositional output was vocal, including eight operas, and numerous oratorios and cantatas. He also wrote a few sonatas and some keyboard music, including pieces meant for keyboard instruction. All of his music, except for one opera, one oratorio, and a few collections of instrumental music, went missing after World War II, but was given back to Hamburg from Yerevan, Armenia, in 1998. This includes four operas and most of the oratorios. The manuscripts are now located at the Staats- und Universitätsbibliothek Hamburg, the former Hamburg Stadtbibliothek (City Library).