I didn't leave physics because of boredom. I left it because other issues compelled me in a bigger way. And I always say to myself, "When I'm 60, I'd like to go back to what I interrupted."

Because of these new car models there is suddenly on the streets of Delhi a new intolerance by the motorists for both the cows and the cyclists. So for the first time the sacred cow in India, which used to be such a wonderful speed-breaker, is now seen as a nuisance. For the first time, I’ve seen cows being hit and hurt. These guys just go right past, and if the cow is sitting on the road, they don’t care. We can’t afford to have a sacred car rather than a sacred cow.

The people who see the population explosion in the Malthusian way - as a geometric progression - forget that population growth is not a biological issue. People are not increasing in numbers out of stupidity and ignorance. Population growth is an ecological phenomenon linked very intimately to other issues, such as the usurpation of the resources which allow people to live.

A single, one-dimensional way of thinking has created a monoculture of the mind. And the monoculture of the mind has become a self-fulfilling prophecy. This is the root of why we have pitted equity against ecology and sustainability against justice.

The liberation of the earth, the liberation of women, the liberation of all humanity is the next step of freedom we need to work for, and it's the next step of peace that we need to create.

It is from the Himalayan forests and ecosystems that I learned most of what I know about ecology.

It's not an investment if its destroying the planet.