Whenever Crosby, Stills & Nash add the mercurial Neil Young to the fold, it makes an already great band only that much better. Retaining the trio's crystalline harmonies, the expanded lineup possesses a versatility that's all its own. During their initial run from 1969 to '74, CSN&Y crafted a fusion of canyon folk, searing political anthems and mind-frying guitar jams that served as the soundtrack for a generation navigating radical social upheaval. The quartet have always proven too volatile to be prolific, yet it's that very volatility that helps make their music so emotionally intense.