the sound: In the first line of Genesis’ seventh release, lead singer Peter Gabriel recites the album’s title with a tense buildup that kicks off an epic hour and a half of music. “And the laaamb … lies dooown … on Broooaaadway,” Gabriel sings in the title track. The double disc album consists of 23 songs, ranging in length from 30 seconds to eight minutes, each characterized by mounting whirlwinds of sounds and words. Alternating between instrumental noise experiments and inspired progressive rock songs, the two-disc album tells the story of a young man named Rael, ostensibly based on Gabriel, who is swept into a bizarre and schizophrenic world of introspection. With dense lyrics that, at times, acquire Tolkein-esque qualities, the narrator invokes vermillion snakes, ravens and “slubberdegullions,” but also references controversial figures from pop culture, such as Lenny Bruce, Marshall McLuhan and Howard Hughes. (“There’s Howard Hughes in blue suede shoes, smiling at the majorettes smoking Winston cigarettes,” Gabriel sings in “Broadway Melody of 1974.”) Concept albums following a semi-fictional character’s rocky lifestyle have been recorded by a number of popular artists, including David Bowie (“Ziggie Stardust”) and Pink Floyd (“The Wall”), but rarely has it been done with such depth and mysteriousness. The music’s tone changes gears repeatedly on “The Lamb,” from lighthearted jingles like “Counting Out Time” to techno puzzles like “The Waiting Room” to weird dialogues like “The Arrival.” But, there are also flashes of good ole 1970s rock ’n’ roll. The band consists of Gabriel on vocals, flute and oboe; Steve Hackett on guitars; Mike Rutheford on bass and 12-string guitar; Tony Banks on keyboards; and Phil Collins on drums, percussion and vibraphone. Moments of instrumental brilliance speckle both discs, including a racing keyboard solo on “In the Cage” and an extended guitar solo on “Here Comes the Supernatural Anaesthetist.” And, although some critics have spurned his later songwriting, Collins is a skilled and inventive drummer who keeps every track interesting.

the background: Recorded and released in 1974, “The Lamb” represents the final chapter of Peter Gabriel’s participation in Genesis. Gabriel and Banks formed the English band 40 years ago, in 1967, when both were young students. By the time “The Lamb” came out, the band already had five studio albums and one live record under its belt, and had recruited Phil Collins as its drummer. Although “The Lamb” climbed to #41 on the U.S. chart (#10 on the U.K. chart), it would be another four years before a Genesis album went platinum. By then, Collins had stepped out from behind his drum set and taken over as lead singer. Although his voice was remarkably similar to Gabriel’s, Collins dramatically toned down the lyrical and musical intensity of the band’s sound. This was largely a reflection of rock trends in the 1970s. In the early part of the decade, English progressive rock was thriving, with bands like Genesis, Yes, King Crimson, The Moody Blues and Jethro Tull riding on the coattails of Pink Floyd’s monumental success. The popularity of “concept” albums was steadily growing, as more bands used thematically intertwined songs to develop complex storylines in the same way as novels and movies. Genesis also incorporated elaborate stage setups into its live performances, wearing bizarre costumes that often made it difficult for Gabriel to sing into the microphone. Stage antics peaked during “The Lamb” tour, and even some fans began to question the band’s direction. With its last Gabriel release, Genesis found itself at the crest of the progressive wave, creating an ingenious work of unfettered energy and experimentation. But, the progressive wave was soon to crash.

the significance: Released the year after Pink Floyd’s progressive masterpiece “The Dark Side of the Moon,” “The Lamb” took concept albums to a new extreme. Although fans and critics are divided about whether the band was better with or without Peter Gabriel, most agree that “The Lamb” represents the creative climax of the Gabriel years. Now one of the top 30 highest selling recording artists of all time, Genesis’ commercial explosion did not occur until after Gabriel departed and Phil Collins took over as front man. (Both Gabriel and Collins have also enjoyed successful solo careers.) As Christian Bale’s demented character explains in “American Psycho,” early Genesis was “too intellectual” for most listeners. Gabriel’s heavy lyrics and over-the-top onstage theatrics were a bit much for mainstream pop fans. In this sense, losing Gabriel was the best thing that could have happened to Genesis. Fresh off a highly successful 2007 reunion tour, Collins and the latter-Genesis gang continue to scoff at accusations that they sold out in the mid-’70s. But, purists will always prefer the highly experimental and wildly imaginative output of the early group, which found its apex with “The Lamb Lies Down on Broadway.”