Nella Larsen's novels Quicksand (1928) and Passing (1929) document the historical realities of Harlem in the 1920s and shed a bright light on the social world of the black bourgeoisie. The novels' greatest appeal and achievement, however, is not sociological, but psychological. As noted in the editor's comprehensive introduction, Larsen takes the theme of psychic dualism, so popular in Harlem Renaissance fiction, to a higher and more complex level, displaying a sophisticated understanding and penetrating analysis of black female psychology.