ans play it. Another belief about the blues, that it is the acid test of a performer's improvising ability, is more accurate for reasons intimately connected with its harmonic structure (Green 121).
Walton positions blues as a formal mode of music at the beginning of the twentieth century because of its connection to the slave music of earlier decades. one aspect of this is the use in what he calls "masked" slave music, which consisted of coded language meant to guide escaped slaves north on the underground railroad. Indeed, the first intersection of the blues with trains as metaphor may be Harriet Tubman's statement that she "never ran my train off the track and I never lost a passenger" (Walton 26). The musical formalization of the blues as of the 1900s owes as much to the oral tradition of slave songs, which basically could not have been written down until there was widespread literacy in the black culture. By the time the blues form was reduced to writing, its structure was quite standard. As Walton explains:
Form, as with all African-derived music, was a function of content rather than the reverse Western model. For this reason formal elements did not get set in Blues until the beginning of the twentieth century with the advent of purely instrumental Blues and the vocal Blues ensemble of the urban areas to which black migrants were attracted. With more than one player, some general prearranged format had to be devised, and thus we have the beginning of the standard A-A B form (Walton 29).
The fact that the first line is repeated verbatim in the blues form is perhaps the single most obvious marker of a blues song as opposed to any other kind. This is a point to which we shall return.
The standardization of form of jazz began in New Orleans, says Walton, because of the highly stratified racial and social structure of the city on one hand and the artistic response to competition for identity. Blues became a par...