Chronicling a campaign day is akin to panning for gold. The shiny nuggets that reporters prize are those rare moments of spontaneity discovered amid the dross of synthetic sound bites and predictable partisan platitudes. That's why the media stars of Wednesday's rollout of the Democratic ticket were the younger children of John and Elizabeth Edwards: Jack, a thumb-sucking, free-spirited, 4-year-old, and Emma Claire, a 6-year-old nervously pretending to be mature for the occasion. Jack and Emma Claire's antics were the one element in the political tableau that not even the most cynical Republican could believe was scripted. Running for president...