The line dividing black gospel and so-called secular music has always been a thin one, and musicians have rarely been afraid to step over it. In the 1920s, the blind singer “Arizona” Juanita Dranes wed ragtime and boogie—rhythms associated with saloons and barrelhouses—to Holiness movement hymns. Later, Mahalia Jackson, who refused to record secular records, nonetheless achieved massive popularity outside the sanctified confines of the gospel scene. A true pioneer, Sister Rosetta Tharpe scandalized the church by performing in nightclubs, practically inventing rock & roll in the process. By the early 1970s, blockbuster Stax singles by the Staple Singers proved artists could exist comfortably in both worlds, or suggested that perhaps these distinct spheres actually overlapped.