I'm not saying I'm impervious to criticism.

America must always lead on the world stage. If we don't, no one else will. The military that you have joined is, and always will be, the backbone of that leadership. But U.S. military action cannot be the only - or even primary - component of our leadership in every instance. Just because we have the best hammer does not mean that every problem is a nail.

We had to get out of Chicago so quick. Election night happens, suddenly I'm talking to Ben Bernanke and Hank Paulson and trying to figure out whether the world's going to fly apart, and Michelle is trying to figure out where the girls are going to go to school. And we pack up and leave and basically our house in Chicago just became like a time capsule. My desk in my home office still had stacks of articles and bills and stuff from 2008.

Few challenges facing America and the world are more urgent than combating climate change. The science is beyond dispute and the facts are clear.

If we choose to keep those tax breaks for millionaires and billionaires, if we choose to keep a tax break for corporate jet owners, if we choose to keep tax breaks for oil and gas companies that are making hundreds of billions of dollars, then that means we've got to cut some kids off from getting a college scholarship.

In America, there's a failure to appreciate Europe's leading role in the world. Instead of celebrating your dynamic union and seeking to partner with you to meet common challenges, there have been times where America has shown arrogance and been dismissive, even derisive.

While the future is unknowable, the winds always blow in the direction of human progress.