Bernstein was an eclectic composer whose music fused elements of jazz, Jewish music, theatre music, and the work of earlier composers like Aaron Copland, Igor Stravinsky, Darius Milhaud, George Gershwin, and Marc Blitzstein. Some of his works, especially his score for "West Side Story", helped bridge the gap between classical and popular music. His music was rooted in tonality but in some works like his "Kaddish Symphony" and the opera "A Quiet Place" he mixed in 12-tone elements. Bernstein himself said his main motivation for composing was "to communicate" and that all his pieces, including his symphonies and concert works, "could in some sense be thought of as 'theatre' pieces".