Jane Lubchenko is a marine biologist and president of the American Association for the Advancement of Science. She tells Judith Strasser that people are just beginning to understand how expensive it would be to try to replace some of the environmental services (soil drainage, water purification, climate control) that the earth provides for free. Also, Columbia University economist Geoffrey Heal tells Steve Paulson about a case where the city of New York was able to cost out the benefit of conserving the ecosystem in the Catskills (where the City collects its water) as opposed to building a water purification plant. And, Jim Fleming reads a bit from Henry David Thoreau's "Walden."

Businessman and environmentalist Paul Hawken thinks our society should do a better job of measuring costs. He tells Anne Strainchamps that both negative events like contracting cancer and positive things like buying a house are counted equally as economic growth. Hawken gives examples of innovative methods of assigning costs that reward concern for the environment.