I found the thread, so no need for me to paraphrase:
"Four hundred years from now, they will be listening to Grateful Dead music like we do Bach. It is the most serious music of the century."
Someone from within the wider Dead community posted quite a thread in response:
"I want to comment on this because it's a claim that deserves consideration, although I don't want to actually litigate the question of "most serious". I will confine myself to a few comments about one aspect of the Dead's music that makes it "serious" — collective improvisation — and their peak period for this, 1972-1974.
First of all, one of the biggest and most idiotic misconceptions about the Grateful Dead and their fans is to miss how serious both the band, and many of their fans, are about music. They have often been caricatured as fumbling hippie noodlers with drugged-out fans who barely care what the band is playing. But the idiocy of this portrayal can be easily discerned when we consider the thousands of hours of live recordings that have long circulated among Deadheads.
Why would stone party animals who don't care about music need all those recordings?
The music the Dead played demands — and amply repays — intense focus and years of careful study. They have been misunderstood because their music is so unique. The dead's collective improvisation is like nothing else in music, 20th Century or otherwise.
First of all, group improvisation — vs. soloing over a rhythm section — is itself relatively rare. Few jazz bands did (or do) it to the same extent, even, and these have been mostly those characterized as free jazz and/or free improvisation.
The great jazz combos of the 60s mostly played much more structured music, whereas the "free" combos generally play stuff that's consistently less structured. The dead were more likely to improvise more or less within a key, and with recognizable themes, although they also played free, atonal, and "noise" music. Other rock bands that improvised together — and there aren't that many — are generally more groove-oriented or repetitious (for instance, Can).
There's nothing wrong with that (I am a fan off Can!), but the point I'm making here is how unique the Dead were.
Every musician in the Dead more or less played lead. It's a huge mistake to look at a Dead performannce as a showcase for Jerry Garcia — this will not only prevent you from understanding their music, but also from understanding Garcia's own playing.
Because we're so used to hearing a guitar solo over rhythm, and because Garcia occupied the upper range and did indeed usually play what sounds like a lead line, there's a tendency to misapprehend what we're hearing when listening to the Dead.
If you want guitar solos, there's Jerry Garcia Band, but that's not generally what's happening with the Grateful Dead.
Consequently, even though their music is often catchy and accessible, it is in a sense difficult to listen to — certainly with any real understanding. You have to listen to all the musicians, and the way they are playing together. Take the time to do this, and you will find that the music is both very serious, and utterly unique.
People who take the time to study and understand this music will come to the conclusion that while the claim that it is the "most serious" music of thee 20th Century is certainly a very strong, tendentious, and perhaps hyperbolic claim, it is far from absurd or indefensible."
