In the span of a few hours, a president will go from celebrating the Super Bowl champions to running meetings on how to fix the financial system, to watching people on TV make up stuff about him, to listening to members of Congress explain why they can’t support a reasonable idea simply because he, the president, is for it, to sitting down with the parents of a young soldier recently killed in action. He spends his day leaping over ravines between vastly different feelings..............

Many if not most of his decisions are thrust upon the president, out of the blue, by events beyond his control: oil spills, financial panics, pandemics, earthquakes, fires, coups, invasions, underwear bombers, movie-theater shooters, and on and on and on. They don’t order themselves neatly for his consideration but come in waves, jumbled on top of each other. “Nothing comes to my desk that is perfectly solvable,” Obama said at one point. “Otherwise, someone else would have solved it. So you wind up dealing with probabilities. Any given decision you make you’ll wind up with a 30 to 40 percent chance that it isn’t going to work. You have to own that and feel comfortable with the way you made the decision. You can’t be paralyzed by the fact that it might not work out.”.........