Twentieth century music can be divided into two large, overarching cycles: the pre-World War II dismantling of past musical structures, and the rapid succession of post-war movements building new musical forms and languages. Perhaps the greatest and most influential development of the first cycle is the innovation of atonality by Arnold Schoenberg and the "Second Viennese School." After 1950, the Avant Garde tested the tolerance of all but a small group of listeners. John Cage began using chance operations (such as tossing I Ching sticks) to direct his compositions, while the collage techniques of Musique Concrete and later the synthesized sounds of Electronic gained increasing prominence as legitimate musical pursuits, and minimalists explored the basics of pitch and timbre. Generally speaking, because of the dissonant and cerebral nature of much post-war music, it declined in popularity but found a welcoming home in universities and conservatories. While art music remains more diverse than before the 1900s, classical works of the twenty-first century have thus far been marked by a return to strong tonality and emotional expressiveness, in a deliberate attempt to reach much larger audiences than the more insular, academic, and dissonant music of last century's Avant Garde. Terms such as New Romanticism, New Populism, and Post-Minimalism have been coined to describe this current thread in classical music. Representative artists of this school include John Adams, Mikel Rouse, Janice Giteck, and Jacob Druckman.