" Aqualung," to many, is Tull's masterpiece. The title track and "Locomotive Breath," with their catchy riffs, would be joined by "My God," "Cross-Eyed Mary," and "Hymn 43" as classic rock staples. There's no arguing with it's commercial success, having sold more than seven million copies and continuing to outsell anything in the back catalog.
Yet, "Aqualung" is arguably Tull's most misunderstood album. Critics dubbed it a concept album, particularly for Anderson's critical, skeptical views of organized religion, mostly on side B ("My God"). Anderson has disputed, almost resented, the assessment seeing the record as "just a bunch of songs." The labeling lead the band to really give the critics a concept album with the following studio release "Thick as a Brick."
"Aqualung" has a dominate theme but is certainly more, much more, than a concept album hindging on a solitary subject. Anderson explores the struggles of the less fortunate in our society (e.g., "Aqualung," "Cross-Eyed Mary," "Up to Me"), teenage angst and formal education difficulties ( e.g., "Wind Up," "Mother Goose"), and returns to his parental themes with "Cheap Day Return, a tune encompassing Anderson's feelings while traveling to visit his sick father.
"Aqualung" also cemented the exaggerated image, especially to those only casually acquainted with the band, that Tull was a "heavy rock" group. Years later, a Grammy for best heavy metal album (viz., "Crest of a Knave") would officially sanction the misconceived stereotype. Yet, "Aqualung" is where Anderson really begins to develop his personal style for acoustical guitar songs with "Cheap Day Return," "Mother Goose," and "Slipstream."
"Aqualung" did establish one of the most notable features of Tull's music: songs varying with intensity, mixing medium to heavy electrical sounds with lighter acoustical passages (e.g., "Aqualung," and "My God"). Indeed, every album up to "Under Wraps" (1984) would have at least one such styled number.
At the end of a brief U.S. tour, drummer Clive Bunker left to get married and form a band called "Jude" with Robin Trower. Anderson recruited Barriemore Barlow. Barlow remained drummer for the next eight years.