THE NATIONAL MALL, DC (WUSA9) -- The rhythm of Dr King's dream has stirred our hearts for decades. So has the music of protest -- then and now.
The two surviving members of Peter, Paul and Mary, who sang 50 years ago, returned to sing again at "Let Freedom Ring" commemoration.
In 1963, their version of "Blowin in The Wind" was the number two hit on the radio. Peter, Paul and Mary asked a haunting question: How long would we have to endure injustice?
It brought the crowd arm in arm to it's feet. "We were not singing it alone," Peter Yarrow says. "We weren't performing it. We were embracing each others hearts with all those people there saying, this is our moment together."
"Music does that," says Noel Paul Stookey. "It binds people together in a way that's irrevocable."
Mary Travers passed away four years ago, but Peter Yarrow and Noel Paul Stookey are still using their music to advance progressive causes.
They returned to the Lincoln steps with Mark Barden, who lost his 7 year old son Daniel in the massacre at Sandy Hook Elementary School... and with the parents of Trayvon Martin, the Florida teen killed by a neighborhood watch captain.
"We are coming here also to say that there must be an end to the kind of violence that brought an end to Dr. Martin Luther King's life," says Yarrow.
"Dr. King was gunned down, and my little son was gunned down in his first grade classroom in Newtown, Connecticut. So we have a long way to go, and we are not going to give up," says Barden.
Peter and Paul are still convinced people working together can change the world. "You don't have to be wealthy, you don't have to be in office. If ordinary people stand together, they can change the course of the way things evolve," says Yarrow.
Dr. King used to quote the abolitionist Theodore Parker to answer the question posed by Peter, Paul and Mary.
"How long? Not long! Because the arc of the moral universe is long, but it bends toward justice."