While Jethro Tull’s 1971 album is peppered with acoustic turns—bowing to jazz-folk heroes like Roy Harper—it’s the sweltering power chords and frontman Ian Anderson’s tough vocals that make it a rock ’n’ roll Goliath. The chugging “Locomotive Breath” and the dirty thump of “Hymn 43” provide metallic KOs, and the rifftastic title tune is a full-on mini-rock opera with gentle breakdowns and tempo shifts. Central themes challenge organized religions, yet there’s a Dickensian quality to many of the lyrics, especially on the grimy “Cross-Eyed Mary,” which details London street urchins.