That Gershwin sought to write a true jazz opera, and that he believed that Metropolitan Opera staff singers could never master the jazz idiom, which could instead only be sung by a black cast, seems to indicate he did not intend the work to belittle African-Americans. Some black singers were overjoyed at Gershwin's work, going so far as to describe him as the "Abraham Lincoln of Negro music". Much of the racial controversy seems to arise from the miscegenation of Gershwin's jazz experience. Gershwin wrote Porgy through an idiom of jazz that was influenced by Western European opera traditions, African-American music, and Russian-Jewish music.