Over the past month or so, we've been running a series of posts highlighting many of the core ideas we discuss on Worldchanging. While it's not necessarily a complete kit of concepts for envisioning 21st century sustainability, each tool, model or idea in the series plays an important role in the conversations we have on the site and with all of you. Below is the full list of 21 principles collected in one place for future reference.

Principle 1: The Backstory
Principle 2: Ecological Footprints and One Planet Thinking
Principle 3: Cradle to Cradle and Closing the Loop
Principle 4: Life Cycle Analysis, Embodied Energy and Virtual Water
Principle 5: Ecosystem Services and Ecological Economics
Principle 6: Transparency
Principle 7: Strategic Consumption
Principle 8: Leapfrogging
Principle 9: Social Entrepreneurship/Base Of the Pyramid
Principle 10: Collaborative Innovation and Creative Commons
Principle 11: Socially Responsible Investment, Patient Capital and Carbon Disclosure
Principle 12: Philanthropy and NGOs
Principle 13: Product Service Systems
Principle 14: Density, Compact Communities and Smart Growth
Principle 15: Carbon Neutrality and Climate Foresight
Principle 16: Offsetting
Principle 17: Environmental Justice
Principle 18: Sustainable Food
Principle 19: Clean and Renewable Energy
Principle 20: Citizen Media
Principle 21: Imagining the Future