The Dutch band Focus earned worldwide renown via their surprise hit "Hocus Pocus." The quirky, mostly instrumental tune shifts back and forth between guitar hero Jan Akkerman's hammering hard rock riffs and keyboardist Thijs van Leer's madcap whistling, yodeling, accordion playing, and more. But beyond the hit's offbeat appeal, Focus came into their own as one of the era's finest prog practitioners, mixing rock and European classical influences with a distinct jazz fusion flavor. Akkerman's axes and van Leer's keys and flute bring vivid life to everything from mellow, melodic tracks to the dazzling 22-minute instrumental prog epic "Eruption."