Subtle Musical Differences

I have to say I don't agree with that, or do I? I don't know, there's a couple of things I'd like to say about classical... What kind of music do we refer to when we talk about classical? I would say we call classical to every form of academic music, from short instrumental pieces and song cycles to big forms are included in the genre, and as part of an academy, classical music follows a pretty stable tradition. For instance, atonal music appeared in Germany circa 1910 and gave birth to 12-tone music by 1923, but it wasn't 'till the 40's-50's that 12-tone music went from an avant-garde scenario and became part of the mainstream... so 12-tone music became some kind of genre, and we call it classical either when it had an avant-garde edge and when it became part of the academy... I guess it's the same with Progressive Rock, a lot of bands were doing progressive music in the 70's and then it became a genre, that's why I'm not so fond of most modern Prog Rock acts, bands like Beardfish or The Flower Kings are pulling of great Progressive Rock, but is it really progressive? I guess that's matter of another discussion... 

Anyway, classical is indeed a naturally progressive genre as rock music is... we call classical to academic music as we call rock to music with electric guitars and stuff... It's a pretty diffuse idea I have and my English domain doesn't really help to be honest, but I wanted to share some thoughts