German composer Arnold Schönberg’s masterpiece Moses and Aaron is a philosophical opera inspired by the biblical characters of the book of Exodus. The plot revolves around the contrasting characters of the two brothers: Moses is an idealist, while Aaron is best described as a man of action. Moses and Aaron is characterised by being a fully dodecaphonic work; Schönberg, author of the music and the libretto, is considered the father of dodecaphonism (or twelve-tone music), a type of atonal music.