It's not just that we are dependent on the natural world for our food and for the very air we breathe-which is, of course, the case-and that the very richness of the natural world continues to provide us with all kinds of assistance.

Being in touch with the natural world is crucial.

An understanding of the natural world and what's in it is a source of not only a great curiosity but great fulfillment.

It's coming home to roost over the next 50 years or so. It's not just climate change; it's sheer space, places to grow food for this enormous horde. Either we limit our population growth or the natural world will do it for us, and the natural world is doing it for us right now.

People must feel that the natural world is important and valuable and beautiful and wonderful and an amazement and a pleasure.

I just wish the world was twice as big and half of it was still unexplored.