American democracy is in grave danger from the changes in the environment in which ideas either live and spread or wither and die.

Having cameras follow you is something that requires a little personal adjustment, but you actually do begin to forget they're there. It's impossible to maintain that awareness all the time, and when you're going through an emotional or absorbing experience, you really don't have any spare attention to think, "Got to remember that the camera is rolling."

This is by far the most serious crisis civilisation has ever faced.

Someone who expresses a view that is contrary to the view of the overwhelming majority should be allowed to stand undisturbed as a monument to our commitment to free speech.

Remember America, I gave you the Internet and I can take it away.

The rule of reason is the true sovereign in the American system.

We ought to approach this challenge [of global warming] with a sense of profound joy and gratitude: that we are the generation about which, a thousand years from now, philharmonic orchestras and poets and singers will celebrate by saying, they were the ones that found it within themselves to solve this crisis and lay the basis for a bright and optimistic human future.