According to the music Historian Daniel Heartz, there has been considerable controversy concerning Gluck's native language. Gluck's protégé in Vienna, the Italian-born Antonio Salieri, says in his memoirs (translated into German by Ignaz von Mosel), that "Gluck, whose native tongue was Czech, expressed himself in German only with effort, and still more so in French and Italian". Gluck's first biographer, Anton Schmid, accepted that Gluck spoke Czech, but thought Salieri incorrect, proposing instead that Gluck learned Czech in Prague. Heartz writes: "More devious manoeuvres have been attempted by Gluck's German biographers of this [the 20th] century, while the French ones have, without exception, taken Salieri at his word. Arend objected that not a single letter written in Czech can be found, to which Jacques-Gabriel Prod’homme countered that no letters written by Liszt in Hungarian were known either, but does this make him a German?" Hans Joachim Moser wanted a lyric work in Czech as proof. In fact, the music theorist Larent Garcin, writing in 1770 (published 1772) before Gluck arrived in Paris, included Gluck in a list of several composers of Czech opéras-comiques (although such a work by Gluck has yet to be documented).