Progressive rock is synonymous with the rise and fall of the Hippie. Long after many of the bands responsible for the creation of the San Francisco Sound split up or moved to Hawaii, prog rock outfits continued to power the avant-garde right up to the time that Punk took over.
The great white whale of prog rock is Emerson, Lake & Palmer. A popular story when I was a kid (whether true, I don't know) was that drummer Carl Palmer's kit was so huge that during one of the band's concerts it collapsed the riser it was on. We snickered and giggled when we heard this. By the mid-to-late 1970s, it was apparent to all but the most die-hard prog-rock devotee that ostentatiousness had got the upper hand of the music.
Precursor to Emerson, Lake & Palmer was a band called The Nice. Originally formed as a backing band for former Ikette P.P. Arnold under the tutelage of Rolling Stones manager Andrew Loog Oldham, The Nice -- Keith Emerson on the Hammond organ; David O'List on guitar; vocalist Lee Jackson on bass; Brian Davison on drums -- were so named because they misheard P.P. Arnold announce them by saying, "Here comes the Naz" -- black American slang for Jesus, the Nazarene -- as "Here comes the Nice."
The Thoughts of Emerlist Davjack (see top of the post), released at the end of 1967, is considered one of the first prog rock albums. With the band's eight-minute-plus reworking of Dave Brubeck's "Blue Rondo à la Turk," infused with a little of Bach's Toccata & Fugue in D Minor, the listener gets a taste of the megalomaniacal classical-rock fusion to come; but mostly the record strikes me as a sonic snapshot of Swinging London. Reason enough to give it a listen.