Optimists are usually wrong. But all the great change in history, positive change, was done by optimists.

It's easy to kind of say it's the elite that's putting you down. Well, it wasn't really the elite, technology will do that.

Once people get a taste for whatever you want to call it - economic independence, a better lifestyle, and a better life for their children - they grab on to that and don't want to give it up.

Two things are going on at the same time with the flattening of the world: The relentless quest for efficiency is squeezing some of the fat out of life.

The poverty fighters resent the climate-change folks; climate folks hold summits without reference to biodiversity; the food advocates resist the biodiversity protectors. They all need to go on safari together.

The philosopher Ludwig Wittgenstein once remarked that if you ask a man how much is two plus two and he tells you five, that is a mistake. But if you ask a man how much is two plus two and he tells you ninety-seven, that is no longer a mistake. The man you are talking to is operating with a wholly different logic from your own.

So what am I? I guess I would call myself a sober optimist...If you are not sober about the scale of the challenge, then you are not paying attention. But if you are not an optimist, you have no chance of generating the kind of mass movement needed to achieve the needed scale.