Without Robert Klein, modern stand-up comedy might not exist.Klein was part of the holy trinity of the stand-up pantheon - along with George Carlin and Richard Pryor - of the post-Beatles era. That rock n roll consciousness proved crucial to the changes the three comedians wrought on what had become a tired, Borscht Belt-and-vaudeville-derived art form.Klein, Carlin and Pryor were all figurative offspring of the late, pioneering Lenny Bruce, who blasted boundaries with his free-associativecomedy, winding up as a free-speech martyr and improv god. Robert Klein hit the main seam, taking observational comedy to new heights by finding the humor in everyday things, whether it was a trip to the dentist or life in high school in the nuclear age.Robert Klein was talking to us: the baby-boom generation that had screamed for the Beatles, postured with the Rolling Stones, grooved to The Mod Squad.It's hard to overestimate how fresh and unexpected Klein's comedy seemed when he first appearedon television. His observational humor - brash, intelligent, edgy without being confrontational - provided a role model for a generation of comedians that followed: Richard Belzer, Billy Crystal, Richard Lewis, Jerry Seinfeld. His first album, Child of the 50s, became a kind of Bible for the comedically-inclined who were following in his footsteps.Klein came from theater: Yale Drama School, to be exact. A Bronx native who graduated high school at 16 and college at 20, he quit Yale because he thought he could make it as an actor in theater in New York. Not quite; but then he auditioned for Second City and spent 14 crucial months learning and performing in Chicago, before returning to New York and Mike Nichol's musical, The Apple Tree.After