There’s a special running in the Contemprary Art Museum in Barcelona at present on the history of Variations in music that you can follow here: http://rwm.macba.cat/en/curatorial?id_capsula=667
I’ve just skimmed over it but it obviously talks of people like John Cage. The thing is organised by Wobbly.
Some here might find it interesting.
New episode on the history of sound collage and sampling coming soon. Meanwhile you can check the previous episodes. Very recommended!!
You can find the series here:
http://rwm.macba.cat/en/curatorial
VARIATIONS #4. The Explosion
MP3: http://rwm.macba.cat/uploads/variations/04_Variations.mp3
Related info: http://rwm.macba.cat/uploads/20100108/04Variations_eng_PDF.pdf
VARIATIONS #3. The Approach
MP3: http://rwm.macba.cat/uploads/variations/03_Variations.mp3
Related info: http://rwm.macba.cat/uploads/20090831/03Variations_eng_PDF.1.pdf
VARIATIONS #2. The Globe
MP3: http://rwm.macba.cat/uploads/variations/02_Variations.mp3
Related info: http://rwm.macba.cat/uploads/20090701/02Variations_eng_PDF.pdf
VARIATIONS #1. Transition
MP3: http://rwm.macba.cat/uploads/variations/01_Variations.mp3
Related info: http://rwm.macba.cat/uploads/20090612/Variations_eng_PDF.pdf