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-minute YouTube clip sent courtesy of a friend.
Note: I first posted this back on April 30, 2007. I am reposting it today because its showing this morning in church convinces me it deserves another viewing! Amen.