This is pretty awesome. The Guitar Player 1975 interview with John. Enjoy! :D
It starts at page 20:
http://www.scribd.com/doc/113254768/Guit...lt-October-2012
Two quotes that stand out:
"I practice all the scales. Everyone should know lots of scales."
"The joy of music is like the joy a runner gets from running, and, musically, I'm running. If music doesn't carry any deep emotion, then what's it for? You find notes that are more joyful to you, and you play them at a fast tempo, and people will get something from it."