Schönberg – a pioneer in music

In his early works Schönberg is a successor of late Romantic composers, e.g. of Richard Wagner. Since 1907 he began to fight against this dependence. He started to abandon tonality, the laws of harmony in their previous functions were dissolved until he composed according to a new principle, i.e. the "method of composition with 12 notes only related to each other". Independent of him and a little earlier, the Austrian composer Josef Matthias Hauer had used a dodecaphonic method since 1919. Earlier composers, e.g. Bach, Mozart and Liszt, had also used all the 12 notes, but the revolutionary element was the placing of the notes functionlessly next to each other without regard to traditional rules. 

Historical development of 12-note music 

Die 3 Wiener Zwölftonschulen