Behind window 3: Prog Rock.
Despised by many to this day, Progressive rock intended to break the boundaries of traditional rock music by bringing in a greater and more eclectic range of influences, musical [folk/jazz/classical], compositional [free-form and experimental], and technological [electronic instruments]. Personally whilst I [as also a fan of Punk Rock] could see the problems that a ‘politics-free’ music in the late 1970’s might represent to more ‘angry’ musicians, I never saw things as an either/or situation.
I guess I was lucky enough to grow up with friends with older brothers and sisters that introduced me at a young age to the likes of Genesis, Pink Floyd, Jethro Tull, King Crimson, Yes, etc. I immediately loved the combination of heavy rock with melodious tunes and rhythms, complex time signatures and changes, lyrical themes based on mythology and surrealism, Concept albums and epic songs that lasted the whole side of an LP, dream inspiring album cover art [best exemplared by Roger Dean].