He was the keynote speaker at Princeton's commencement in 2012. There, he delivered a speech that urged students to remember that they are lucky — not naturally superior to others.
From the speech:
All of you have been faced with the extra cookie. All of you will be faced with many more of them. In time you will find it easy to assume that you deserve the extra cookie. For all I know, you may. But you'll be happier, and the world will be better off, if you at least pretend that you don't.
Never forget: In the nation's service. In the service of all nations.