Hemispheres is Rush at their imperial best. It's a supremely confident album of pinwheeling prog rock, bookended by two long tracks—“Cygnus X-1 Book II: Hemispheres” and “La Villa Strangiato”—that skip through musical themes, tumbling pell-mell from languid calm to folky innocence (“The Trees”) to rapid-fire, stop-start riffing of remarkable nimbleness. Their trademark blazing interplay of instruments is particularly notable in the gonzo “Circumstances”, which condenses the assault into one frenzied scattershot attack.