A 1957 photo showing, left to right, Rev. Martin Luther King, Jr., Pete Seeger, Charis Horton, Rosa Parks, and Rev. Ralph Abernathy at the Highlander Folk School in Monteagle, Tennessee. It is thought to be the only photograph of King, Seeger, Parks, and Abernathy together. The school was a training ground for the civil rights movement. Parks herself trained in the library pictured above shortly before her fateful refusal to give up her seat on a Montgomery city bus in 1956, the act of civil disobedience that touched off the 381-day Montgomery Bus Boycott. Charis (pronounced with a hard "c") is the daughter...