This is fascinating. I never realized before that almost all Negro spirituals can be played exclusively on the black keys of the piano, i.e. using the Pentatonic scale. See for example, "Swing Low, Sweet Chariot" and "Every Time I Feel the Spirit." Nor did I know that the melody of Amazing Grace is a slave melody, probably a West African sorrow chant. This all from a Wintley Phipps' 8 ninute YouTube clip sent courtesy of a friend.