Many slave spirituals--songs such as "Swing Low, Sweet Chariot," "Michael, Row the Boat Ashore," and "Go Down, Moses"--have become interwoven into the fabric of American culture. For centuries these deeply moving songs were sung by slaves as they worked in the fields. In 1871, six years after the end of slavery, a group from Fisk University known as the Jubilee Singers toured the United States and abroad, raising money for their bankrupt school and,...