Ken Emerson talks about the subject of his new biography, Stephen Foster. Foster was a nineteenth century songwriter who had a strong impact on American music. He was the composer of many familiar songs including, "Oh! Susanna," "Camptown Races," and "Jeanie with the Light Brown Hair." Emerson says Foster was heavily influenced by black music. And even though the music was often performed in the offensive black-face style, his songs sometimes betray a sympathy for African-Americans.