Dave Matthews' between-song banter devolved almost as quickly as the mental capacity of those campers experimenting with mind-altering substances in Rothbury's Sherwood Forest. At the onset of the nearly three-hour performance he talked about the weather in mundane terms ("What a beautiful day"), but less than 30 minutes later he was riffing about laying in a hammock and trying to "touch the moon with [his] tongue." Surprisingly, as his stage presence grew more unhinged, the group's musical explorations tightened. A galloping "Tripping Billies" mixed mirth ("Eat, drink and be merry…") and morbidity ("…for tomorrow we die."); "So Damn Lucky" built to a dizzying, horn-fueled climax; a true-to-its-source take on Peter Gabriel's "Sledgehammer" proved a smart selection, as violinist Boyd Tinsley sawed at his instrument as if he was trying to start a fire.