I think whats becoming clear here is that blues music as well as any other kind of music means different things to different people.

I know there are variose styles of blues music in a variety of tempo's,some actually on the edge of jazz.

But have to say that for me what tipifies blues is the soulfull expressing of a persons sadness. i dont mean to sound like a manic depressive here but i realy do think
( be it right or wrong )that the origins of blue music derives from opression, povity and general bad times.

i do take the point that i may have generalised a bit when refereing to blues music being all sad, but i think that youll agree that the greater majority of blues is in fact mornful