Tom Hayden was there in 1968, in Chicago for the Democratic National Convention. He was one of the Chicago Seven charged with inciting the riots.

As regards to '68,

"It simply didn't have to happen," Hayden says of the Chicago chaos, 40 years later. "It takes two for a riot to occur. And if it wasn't for the FBI advisers, Chicago '68 would not have happened - repeat, would not have happened."

In regard to '08,

"...there's really no comparison to 2008, he says."

In '68, the Democratic Party was prolonging a war where hundreds of young men were dying every week. Martin Luther King Jr. and Bobby Kennedy were both assassinated shortly before the convention.

Let's hope both sides will stay calm this time around. A preview, Yippies with 'peace bats'.