There are certain riffs that are forever emblazoned within the soundtrack of rock 'n' roll: the Beatles' "Day Tripper," the Stones' "Satisfaction," the Kinks' "You Really Got Me," Cream's "Sunshine of Your Love," and Hendrix's "Purple Haze." Then there's that opening guitar lick to "Locomotive Breath," the inevitable showstopper in any Jethro Tull concert. While Aqualung, the concept album that boasted that little ditty, may be the disc that endeared Tull to the masses, the band possesses a lot more credence than any single song. But then they've always been somewhat misunderstood as well. For starters, JT isn't that leering front man/flutist who makes a habit of balancing precariously on one leg. That would be Ian Anderson, who also assumes the role of singer, songwriter, and the band's sole constant since their formation nearly 40 years ago. (For the record, their name's derived from an 18th-century English inventor of agricultural tools.) OK, so the tally of Tull players past and present rivals the number of times Florida's politicos have flip-flopped on property tax reform. But they're a hell of a band and have 11 platinum and five gold albums as proof that they're doing something right. They've also got a repertoire that freely mingles rock, folk, classical, blues, and literary observations with revelry and panache.