The global conservation organisations are doing everything they can on modest budgets. They essentially promote setting aside reserves and parks around the world.

In science, you really do need to have a purpose-driven life. You will succeed to the extent that you get the most out of your career so that you can give the most back. Try to be an addict, driven to achieve discoveries, learning new things, and then writing about them.

It's obvious that the key problem facing humanity in the coming century is how to bring a better quality of life - for 8 billion or more people - without wrecking the environment entirely in the attempt.

Progress, then, is a property of the evolution of life as a whole by almost any conceivable intuitive standard.... let us not pretend to deny in our philosophy what we know in our hearts to be true.

I had in mind a message, although I hope it doesn't intrude too badly, persuading Americans, and especially Southerners, of the critical importance of land and our vanishing natural environment and wildlife.

The brain and its satellite glands have now been probed to the point where no particular site remains that can reasonably be supposed to harbour a nonphysical mind.

The commitment must be much deeper - to let no species knowingly die; to take all reasonable action to protect every species and race in perpetuity.