I am with Whistlestop on this, all the way (sorry, I know it would be more fun if we disagreed, but...)

I have sat through enough blues Festivals to seriously question the insights of anyone who thinks that is is hard to define what the blues is--or what it is not--it seems pretty clear to me--

As a musician, I am fascinated by the each of the elements of the the blues, and especially by the way that complex music can be created by interlacing such simple elements--

The blue note, or notes, (because there are several tasty little intervals that you can bend) open up a different world when you understand the simple tricks that dictate the way they are used--

And of course, the blues bass figures, which seem to have re-defined all of popular music--

Mostly though, blues is a system that gives you the tools to be creative with musical ideas in a way that is difficult with other musical forms--

Mbo, sorry to disappoint your ethnomusicology instructor, but blues is not a state of mind, is is a set of rules that almost anyone can use to create and express musical ideas--