You can only get really unpopular decisions through if the electorate is convinced of the value of the environment. That's what natural history programmes should be for.

No one will protect what they don't care about, and no one will care about what they have never experienced.

The truth is: the natural world is changing. And we are totally dependent on that world. It provides our food, water and air. It is the most precious thing we have and we need to defend it.

Instead of controlling the environment for the benefit of the population, perhaps we should control the population to ensure the survival of our environment

What humans do over the next 50 years will determine the fate of all life on the planet.

Anyone who believes in indefinite growth on a physically finite planet is either mad or an economist

The World is full of wonders, but they become more Wonderful, not less Wonderful when Science looks at them.

The question is, are we happy to suppose that our grandchildren may never be able to see an elephant except in a picture book?

How could I look my grandchildren in the eye and say I knew what was happening to the world and did nothing.

Bringing nature into the classroom can kindle a fascination and passion for the diversity of life on earth and can motivate a sense of responsibility to safeguard it.

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

Then I have some bad news for you, because humans are going to destroy each other as soon as it becomes easy enough to, which will be very soon.

Sometimes we're loyal to more than one thing. When there's a conflict, we have to choose which loyalty to honor.

Our whole family assembles in Chicago at Christmas and usually in Aspen in the summer.

Too many Christians are living in a house of fear and not in the house of love.

It is absolutely important that we have a unified alliance and that we explain to the Russians that you cannot be a 21st-century superpower, or power, and act like a 20th-century dictatorship.

The slideshow "is a very primitive form that quickly becomes predictable and repetitive."

We have our own thoughts, and if we want others to know them, we must tell them.

People say I pay too much attention to the look of a movie but for God's sake, I'm not producing a Radio 4 Play for Today, I'm making a movie that people are going to look at.

In separateness only does love learn definition.

Everything speaks: the flowing airstream and the sailing halycon, the blade of grass, the flower, the bud, the element; did you imagine the universe to be otherwise?