I heard the author of this blog,
jazzwax.com, on the local NPR station this morning. He is also the author of a book,
Why Jazz Happened, in which he identifies some of the social and technological changes that affected the development of the art. Fascinating stuff for you jazz fans out there.
Note: He identified "In a Silent Way" as one of the great jazz albums, so he has some credibility with me.
Regards,
D-Ray