From the beginning of the century, when W. E. B. DuBois analyzed the “souls of black folk” in his extremely influential book of 1903, African-American social movements have been closely identified with particular forms of musical expression. There had been other books which collected and represented the songs of African-Americans, such as the abolitionist era's Slave Songs of the United States (1867) and James Monroe Trotter's Music and Some Highly Musical People (1878), but DuBois's book put these songs in a social and historical context, and tried to give them clear political meaning. DuBois saw in what he termed the “sorrow songs” a central signifier of black culture, and he saw the spirituals as a central aspect of his own identity as a black man in the United States. As he wrote, “They that walked in darkness sang songs in the olden days – Sorrow Songs – for they were weary at heart … Ever since I was a child these songs have stirred me strangely.