My dad challenged every president from President [Dwight] Eisenhower and Vice President [Richard] Nixon to President [J.F] Kennedy, Vice President [Lindon] Johnson to President Johnson and Vice President [Hubert] Humphrey. It`s challenging the administrations to do the right thing.
We'll continue to speak out in a respectful way; never challenging somebody's love for America when you criticize their strategies or their point of view.
Whenever I look at the history of presidents I deeply admire - the one thing that I'm always struck by is persistence. It's a quality that's underrated. Being able to plough through, being able to stay buoyant in the face of challenges.
Today I challenge our nation to commit to producing 100 percent of our electricity from renewable energy and truly clean carbon-free sources within 10 years.
As a matter of fact, it's in our interests that we help reformers across the Middle East achieve their objectives. This is the fundamental challenge of the 21st century.
We will build our defenses beyond challenge, lest weakness invite challenge. We will confront weapons of mass destruction, so that a new century is spared new horrors.
Courage is resistance to fear, mastery of fear - not absence of fear. So many look to eradicate fear from their lives, when that is an impossible task. You can certainly experience moments in absence of fear, however accept that fear will be with you whenever you are in the process of living creatively. The challenge is to go ahead regardless, simply notice the feeling and manage being courageous.
I may have absolutely no control over what happens to us, but we can control how we respond. If we choose the right attitude, we can rise above whatever challenges we face.
I remember, right after Hezbollah launched its rocket attacks on Israel, I said: This is a clarifying moment; this is a chance for the world to see the threats of the 21st century, the challenge we face.