By preventing dangerous asteroid strikes, we can save millions of people, or even our entire species. And, as human beings, we can take responsibility for preserving this amazing evolutionary experiment of which we and all life on Earth are a part.

We need early warning systems, technologies to deflect an asteroid - and we need political preparedness as well. It needs to be clear who is to decide what, who launches the rockets, who presents which bills to its citizens. This is a planetary decision. We need to do this all together. Or it will not happen.

This whole issue of limits to growth, which provides a psychological, as well as a physical, cap on potential expansion of activity and awareness, has had a very depressing effect on many people.... I don't for a moment think that there's any concept which anyone's working with now which will be followed as a straightforward scenario. But the idea embodied in concepts such as space colonization or space industrialization, or availability of nonterrestrial resources, is fundamental, and it will change the way in which people look at the future.

It is not enough to do a desktop exercise of a Beethoven symphony. You need to practice with an orchestra. The musicians need to read the notes. Otherwise it will be a disaster.

We could not wipe ourselves out with a nuclear war. I do not want so sound too positive. It would be a catastrophe, but it would not be a final one. We are not powerful enough for that. An asteroid could be that powerful. That is why we need to do our homework.

While we didn't know the dinosaurs personally, we do know that they were wiped out by an asteroid impact.

As you pass from sunlight into darkness and back again every hour and a half, you become startlingly aware how artificial are thousands of boundaries we've created to separate and define. And for the first time in your life you feel in your gut the precious unity of the Earth and all the living things it supports.