Cities are responsible for the vast majority of the creation of the economy. They're also places into which we pour the vast majority of resources, the vast majority of energy and the places where a huge percentage of the decisions about how systems are built and how products designed, etc., happen.

I think there's a gigantic generation gap in terms of how people understand the Internet and how much they think technology is an important factor in social change.

You don't change the world by hiding in the woods, wearing a hair shirt, or buying indulgences in the form of 'Save the Earth' bumper stickers. You do it by articulating a vision for the future and pursuing it with all the ingenuity humanity can muster.

Deep walkability describes a city that is built in such a way that you can move from one area to another on foot, on bicycle, on transit and have an experience that remains a pleasant one, that you feel you are welcome not just in the neighborhood but moving between neighborhoods.

There's no law of physics that says we have to be an unsustainable society - in fact, quite the opposite. The planet's ready to work with us if we're ready to think differently, but we do have to make that jump and start to do things in new ways.

There’s more to being an environmentalist than occasionally signing an online petition and mailing your check to the Sierra Club. Really the most effective environmental actions you can take have to do with crafting your home and surroundings, your workplace decisions and your investment habits.

I think we're going to start to see a new model of civic advocacy where people get together once in a while to protest, but it's more about an ongoing, sustained engagement in issues, networks and communities about which people care.