In the course of a healthy debate, we prioritize different goals, and the different means of reaching them. But without some common baseline of facts, without a willingness to admit new information and concede that your opponent might be making a fair point, and that science and reason matter - then we're going to keep talking past each other, and we'll make common ground and compromise impossible.

It's hard to anticipate. I can tell you what I'm feeling right now is that I'm busier than I expected these last two weeks. A great deal of emotion around the people that I've worked with and the gratitude I feel for the sacrifices they've made on behalf of the American people, but also on behalf of me personally.

We're up against the conventional thinking that says your ability to lead as president comes from longevity in Washington or proximity to the White House. But we know that real leadership is about candor and judgment and the ability to rally Americans from all walks of life around a common purpose, a higher purpose.

Constitution is a living document; no strict constructionism.

The biggest threat that we face right now is not a nuclear missile coming over the skies. It's in a suitcase. This is why the issue of nuclear proliferation is so important. It is the - the biggest threat to the United States is a terrorist getting their hands on nuclear weapons.

When I came into office, the world was divided. Iran was resurgent. Iran is at its weakest point, economically, strategically, militarily, then since - then in many years. And we are going to continue to keep the pressure on to make sure that they do not get a nuclear weapon. That's in America's national interest and that will be the case so long as I'm president.

I confess to wincing every so often at a poorly chosen word, a mangled sentence, an expression of emotion that seems indulgent or overly practiced. I have the urge to cut the book by fifty pages or so, possessed as I am with a keener appreciation for brevity.