So don't get cynical. Cynicism didn't put a man on the moon. Cynicism has never won a war, or cured a disease, or built a business, or fed a young mind. Cynicism is a choice. And hope will always be a better choice.

We seem to have trouble with [critical thinking]. And our political system doesn't help.

Physically, I feel probably as good as I've ever felt. And I've got as much energy as I ever did. But what you feel after eight years - and I think you'd feel this no matter what, but anytime you have a big transition, it gets magnified - is time passes.

In the campaign back in 2007, 2008, people would say, "Oh, he's being naïve. He thinks that there's no red states and blue states. And wait 'til he gets here." And I will confess that, I didn't fully appreciate the ways in which individual senators or members of Congress now are pushed to the extremes by their voter bases. I did not expect, particularly in the midst of crisis, just how severe that partisanship would be.

Granting such immunity undermines the constitutional protections Americans trust the Congress to protect.

For the world has changed, and we must change with it

We can't get to the $4 trillion in savings that we need by just cutting the 12 percent of the budget that pays for things like medical research and education funding and food inspectors and the weather service. And we can't just do it by making seniors pay more for Medicare.