Arnold Schwarzenegger came into the governorship seven years ago believing that he could succeed where his predecessors had failed in dealing with California's thorniest issues. He'll leave office in a few months, having learned the hard way that California is difficult, and perhaps impossible, to govern. Its ever-expanding economic and cultural complexity collides with a politics so ossified and diffused, with so many officeholders and institutions sharing authority, that no one is truly accountable for outcomes.