He was the ultimate bulls--- detector. Comedians love an even playing field in life, which there never is. Anytime there wasn't one, he was quick to point it out. I love his bit about omelets: You kill a person, it's an abortion; you kill a chicken, it's an omelet. How did we become better than chickens? Who made this rule up?
I'd kind of been waiting to see what Rock would have to say, because I remember one of his HBO specials (I think Bring the Pain, but don't quote me) beginning with a montage of covers of comedy albums that had influenced him--Cosby's To Russell, My Brother, Whom I Slept With, for example. And Carlin's Class Clown.
One of my memories of George Carlin is of seeing him on TV at some awards ceremony--I think the Grammys, but again I'm not 100% sure. Whatever the award, they were doing that "close-ups of the nominees" thing in a category where an album of Carlin's was nominated alongside, among others, an album of Rock's.
Rock won, and--either Carlin was a better actor than he ever got a chance to show us--or else he genuinely loved seeing the younger comedian succeed, because he broke out into a big, seemingly genuine smile.
Either way, it makes it even more the shame that he's died.