Citizen service is the very American idea that we meet our challenges not as isolated individuals but as members of a true community, with all of us working together. Our mission is nothing less than to spark a renewed sense of obligation, a new sense of duty, a new season of service.

A preemptive action today, however well-justified, may come back with unwelcome consequences in the future. And because... I've done this. I've ordered these kinds of actions - I don't care how precise your bombs and your weapons are, when you set them off, innocent people will die.

When I took office, only high energy physicists had ever heard of what is called the Worldwide Web... Now even my cat has its own page.

Cooperation will save the future. And America should lead it. Every time humanity has been in danger of extinguishing itself, our consciousness and our conscience have led us to come together. That's the big issue of the 21st century.

Running helps me stay on an even keel and in an optimistic frame of mind.

That all depends on what "is" is.

We cannot idealize technology. Technology is only and always the reflection of our own imagination, and its uses must be conditioned by our own values. Technology can help cure diseases, but we can prevent a lot of diseases by old-fashioned changes in behavior.