or else whose approach is a hybrid of disparate styles, or incorporates unorthodox, new, distinctly unique ingredients. Important cultural trends often informed music of this period, romantic, modernist, neoclassical, postmodernist or otherwise. Igor Stravinsky and Sergei Prokofiev were particularly drawn to primitivism in their early careers, as explored in works such as The Rite of Spring and Chout. Other Russians, notably Dmitri Shostakovich, reflected the social impact of communism and subsequently had to work within the strictures of socialist realism in their music. Other composers, such as Benjamin Britten (War Requiem), explored political themes in their works, albeit entirely at their own volition. Nationalism was also an important means of expression in the early part of the century. The culture of the United States of America, especially, began informing an American vernacular style of classical music, notably in the works of Charles Ives, John Alden Carpenter, and (later) George Gershwin. Folk music (Vaughan Williams' Five Variants of Dives and Lazarus, Gustav Holst's A Somerset Rhapsody) and jazz (Gershwin, Leonard Bernstein, Darius Milhaud's La création du monde) were also influential. In the last quarter of the century, eclecticism and polystylism became important. These, as well as minimalism, New Complexity, and New Simplicity, are more fully explored in their respective articles. Styles Romantic style At the end of the 19th century (often called the Fin de siècle), the Romantic style was starting to break apart, moving along various parallel courses, such as Impressionism and Post-romanticism. In the 20th century, the different styles that emerged from the music of the previous century influenced composers to follow new trends, sometimes as a reaction to that music, sometimes as an extension of it, and both trends co-existed well into the 20th century. The former trends, such as Expressionism are discussed later. In the early part of the 20th century, many composers wrote music which was an extension of 19th-century Romantic music, and traditional instrumental groupings such as the orchestra and string quartet remained the most typical. Traditional forms such as the symphony and concerto remained in use. Gustav Mahler and Jean Sibelius are examples of composers who took the traditional symphonic forms and reworked them. (See Romantic music.) Some writers hold that Schoenberg's work is squarely within the late-Romantic tradition of Wagner and Brahms and, more generally, that "the composer who most directly and completely connects late Wagner and the 20th century is Arnold Schoenberg".