The essential tunes by the Sixties' first true supergroup a cynic would be tempted to subtitle this collection And Definitely Not Young. But before CSNY, there was only CSN — the original late-Sixties harmonic convergence, often dysfunctional, more often magical. Composed of former Byrd David Crosby, Buffalo Springfield's Stephen Stills and runaway Holly Graham Nash, CSN were the first supergroup worthy of the tag, thanks to early showcases like "Suite: Judy Blue Eyes" and "Marrakesh Express." Where earlier groups such as the Everly Brothers and the Beach Boys offered brotherly blends of harmony, CSN introduced a revolutionary chemistry of varied voices and songwriting styles. Neil Young gave the group an extra explosiveness, but this set spotlights CSN's core power and proves that their promise wasn't wasted along the way.