In July of 1791 he was deep in work on his opera The Magic Flute when a mysterious stranger,dressed all in gray,came to the house to ask him to compose a requiem mass.

• 1791年7月，他正埋头于歌剧《魔笛》的写作，一个全身穿着灰色衣服的、神秘的陌生人来到他家，请他作一支安魂弥撒曲。