It rained on Bill Clinton's parade -- and on a host of gathered Democratic luminaries -- in Little Rock earlier this month. The opening of Clinton's new presidential library, a disconnected bridge to the 21st century, was a largely sodden show. A military man gamely held an umbrella above the former president's already wet head, and the singer Bono's sunglasses were doing double duty as water shields. A day later, a photo preserved the sight of George W. Bush and Bill Clinton jammed together in a doorway, each intending to go first (Clinton won). It brought to mind the shadow-boxing...