The relationship between human progress and its effect on the natural environment has long been a contentious issue.Even before the first glorious ring of the Liberty Bell, America was a land of freedom and promise. The Cornerstones of Freedom series explores what inspires people from all over the world to start life anew here, endure the economic and social upheavals, and defend the land and rights that are unique to the United States of America. This book details the history of the environmental movement in the United States, from its first stirrings in the writings of Henry David Thoreau and George Perkins Marsh to recent debates over climate change and energy sources.