If we want America to stay on the cutting edge, we need young Americans to master the tools and technology that will change the way we do just about everything.

I am a firm believer that you don't do anything significant by yourself. Again, maybe there are exceptions. There's the Picasso or the Mozart.

Hope -- Hope in the face of difficulty. Hope in the face of uncertainty. The audacity of hope! In the end, that is God’s greatest gift to us...A belief in things not seen. A belief that there are better days ahead.

I do think that I am generally optimistic.

I just want people to know the facts and science and the information... measles is preventable.

I would have I think made a bigger mistake if I had said, "Eh, chemical weapons. That doesn't really change my calculus." I think it was important for me as president of the United States to send a message that in fact there is something different about chemical weapons [in Syria].

When times change, so must we.