Given the thunder of Seconds Out and the breathtaking scope of Three Sides Live, it’s easy to forget about Genesis’ first live album — a five-track set originally released as a record company stopgap in 1973. But Genesis Live remains an essential stage document — the sound of a band realizing its massive potential. The two tracks from 1971’s Nursery Cryme (the eerie “Musical Box” and shape-shifting “Return Of The Giant Hogweed,”) improve vastly on the poorly recorded originals: Here, Gabriel’s theatrical stage presence is magnetic, even without the visual benefit of old man masks. (Hackett’s menacing guitars, meanwhile, are finally audible.) The Foxtrot material falls a bit short — the jittery counterpoint of “Watcher of the Skies” is notoriously tricky to translate on-stage. But it’s worth the admission price solely for the climactic “The Knife.” This show-stopping take, led by Collins’ manic cymbals and whistle, makes the original sound downright limp.