The 75% of the classic 1960’s folk-rock quartet that’ll show up for this gig are, collectively, the most important part: David Crosby, Stephen Stills, and Graham Nash were the anchors of the group even after the addition of Neil Young in 1969, penning smashes like Teach Your Children and Southern Cross while on their way to defining the meaning of 1960’s folk and acting as a West-coast counterpart to the Greenwich Village scene inhabited by Dylan and Joan Baez.