DAVID WEIGEL’S “The Show That Never Ends: The Rise and Fall of Prog Rock” has an impossible job: to elucidate 20 years of musical history in 350-odd pages. To make matters worse, Mr Weigel must do this with a genre of music unfamiliar to the average reader thanks to a dearth of hit singles, radio play or cultural touchstones. Prog (progressive) rock is ambitious, difficult, long-form, often instrumental music that freely mixes high and lowbrow elements and is frequently created by musicians with long hair, tall boots and monster chops. Despite its success in the 1970s, prog rock remains trapped in amber: listening to a 20-minute song with subtitled movements is no longer the norm.

If the fall of prog at the brass-knuckled hand of punk is well known, its beginnings are less so. Mr Weigel finds the genre’s birth in the heart of the 1960s psychedelic era: the progenitors of prog were young, talented and unsatisfied with the typical three-minute song structure. In their desire to chart new territory, they threw away the map. Labels allowed bands to experiment, and prog was lauded by critics who recognised the ambition.

It is a shame that Mr Weigel devotes so little time to his descriptions of the scenes at the Marquee, UFO and Middle Earth clubs in London, and his sketches of the watershed proto-prog albums by The Beatles, The Moody Blues, Procol Harum and Pink Floyd feel cursory. He is anxious to move on to the main players in the Canterbury scene that blossomed when Kevin Ayers, Daevid Allen, Richard Sinclair and Robert Wyatt, a close-knit band of hippies, collectively founded The Soft Machine, Caravan and Gong, among other outfits legendary among the prog cognoscenti.

From this communal house, Mr Weigel pivots to his exemplar, King Crimson (in prog circles, there is King Crimson and then there is everybody else). Mr Weigel uses Robert Fripp, the band’s leader and experimental guitarist, as his Great Man of Prog—much like Ken Burns deployed Louis Armstrong to try and explain all of jazz. Mr Weigel traces Mr Fripp’s every movement and collaboration, depicting him as prog’s invisible hand, motivated by infallible intuition. It is a convenient trope, but eventually it gets tiresome.

To round out the book, Mr Weigel outlines the careers of his other first-tier prog bands: Yes, Genesis and Emerson, Lake, & Palmer (his prog is largely an English phenomenon: no Captain Beefheart or Frank Zappa here). Along the way, the author throws in passing nods to Rush, Jethro Tull, Mike Oldfield and Van der Graaf Generator, with just the barest mentions of Magma, Gentle Giant, Hawkwind and Tangerine Dream (the pace of the material leaves the reader feeling not so much sitting in the studio as viewing it from a high-speed train). Even still, the overlooking of titles such as “Tommy” by The Who, Pink Floyd’s “Dark Side of the Moon” and Queen’s “Bohemian Rhapsody” is glaring. These are works that should be considered at the heart of prog by any criterion—unless the genre’s definition is marked by the obscure and unknown.

But Mr Weigel’s book still succeeds as a defence of a much-maligned genre. It asks: what’s wrong with long instrumental or symphonic sections? What’s wrong with concept albums? What’s wrong with being a virtuoso? What’s wrong with making use of found sounds? Prog bands, despite any sins—real or imagined—did some brave and musically adventurous deeds. They illuminated the future by shining a light backwards onto classical, folk and jazz elements. They wrote songs that weren’t about love, but about self-discovery or communion with the divine, and couched these ideas in bizarre, dystopian Tolkien-meets-Heinlein dreamscapes. The results were something totally new.

The hope of a book like “The Show That Never Ends” is not only to extol Keith Emerson’s hands, Peter Gabriel’s wardrobe or Jon Anderson’s elfin tenor. It works as an invitation to explore the dark corners of prog: its international reach, its cultish esotericism and its fondness for ostentatious album covers adorned with flying teapots, armadillo tanks and fantasy landscapes as detailed as the music.

Will this book inspire a comprehensive re-evaluation of prog by critics, or win the genre legions of new fans? Will it turn readers towards the contemporary post- and neo-Prog scenes? Probably not. What is hoped for is that music fans fatigued by cut-and-paste Pro Tools songs might prick up their ears when they catch King Crimson’s “21st Century Schizoid Man” sampled by Kanye West (“POWER”), or hear Rush at a baseball game. They may even find themselves downloading an album out of curiosity. Books like these are a testament to a period of music-making that struck a chord, and serve as proof that prog didn’t die out with Moogs, mellotrons and double-necked guitars. As Mr Weigel succinctly states, this was “music that copied nothing, and could be replicated by nobody”.