Yes, this is hard. But there should be no question that the United States of America is stepping up to the plate. We recognize our role in creating this problem; we embrace our responsibility to combat it. We will do our part, and we will help developing nations do theirs. But we can only succeed in combating climate change if we are joined in this effort by every nation - developed and developing alike. Nobody gets a pass.

Their foreign policy is so disjointed, confusing, and chaotic that, really, people need to reexamine those who want to be involved in every war.

One of the things you learn as president is, as powerful as this office is, you have limited bandwidth. And the time goes by really quickly and you're constantly making choices, and there are pressures on you from all different directions - pressures on your attention, not just pressures from different constituencies. And so you have to be pretty focused about where can you have the biggest, quickest impact.

The United States will do what we must to prevent Iran from obtaining a nuclear weapon.

Like no other illness, AIDS tests our ability to put ourselves in someone else's shoes - to empathize with the plight of our fellow man. While most would agree that the AIDS orphan or the transfusion victim or the wronged wife contracted the disease through no fault of their own, it has too often been easy for some to point to the unfaithful husband or the promiscuous youth or the gay man and say This is your fault. You have sinned. I don't think that's a satisfactory response. My faith reminds me that we all are sinners.

And if we walk away now, if we simply retreat into our respective corners, we will never be able to come together and solve challenges like health care, or education, or the need to find good jobs for every American.

We can lose so much of what we've gained in terms of the kind of democratic freedoms and market-based economies and prosperity that we've come to take for granted.