In his quest to take up the slogan of the Stieglitz group, "Affirm America", Copland found only the music of Carl Ruggles and Charles Ives upon which to draw. Without what Copland called a "usable past" in American classical composers, he looked toward jazz and popular music, something he had already started to do while in Europe. In the 1920s, Gershwin, Bessie Smith, and Louis Armstrong were in the forefront of American popular music and jazz. By the end of the decade, Copland felt his music was going in a more abstract, less jazz-oriented direction. However, as large swing bands such as those of Benny Goodman and Glenn Miller became popular in the 1930s, Copland took a renewed interest in the genre.