Crosby Stills Nash & Young

"At this point, it's not about would we get together," he says. "Should we, is the important question."

Fillmore East performance arrived a little more than a month after their famous Woodstock appearance.

Defining folk rock is a paradoxical task, to say the least.

He wrote "I Watched It All Come Down" to express his regret they didn't do more together.

"His legacy will continue to live on through his legendary music," Crosby's wife said in a statement.

Four CDs will feature numerous outtakes, unheard alternate versions and an appearance from Joni Mitchell.

Seldom in rock history have four guys who seemingly couldn’t stand each other sounded so good together.