The heart of the security agenda is protecting lives, and we now know that the number of people who will die of AIDS in the first decade of the 21st Century will rival the number that died in all the wars in all the decades of the 20th century.

There is the natural tendency that all of us are vulnerable to, to deny unpleasant realities and to look for any excuse to push them away and resolve to think about them another day long in the future.

You can say the Earth is flat, but it doesn't mean you're going to fall off the edge.

We have to abandon the conceit that isolated personal actions are going to solve this crisis. Our policies have to shift.

Anyone who deals with the climate crisis has an internal dialogue between hope and despair, because the challenge is so huge and the danger is so great and the stakes are so high. But I have always resolved that in favour of hope, and actually I'm more hopeful now than I was a decade ago when the solutions were visible on the horizon, but you had to seek reassurance that the technology experts that they're coming, they'll be here.

Any of us who work on the task of solving the climate crisis have at times an internal struggle between hope and despair. But that's one of the things that connects this climate movement to the previous great moral revolutions, like the civil rights movement and more recently the gay rights movement. So those who feel despair should be of good cheer, as the Bible says. Have faith, have hope. We are going to win this.

Our democracy, our constitutional framework is really a kind of software for harnessing the creativity and political imagination for all of our people. The American democratic system was an early political version of Napster.