Beginning with Thoreau, Frederick Law Olmsted, and George Perkins Marsh, Strong shows that conservation enjoyed the support of a few writers and scientists even in the heyday of land development in the mid-nineteenth century. Later chapters are devoted to John Wesley Powell, who after the Civil War attempted to introduce enlightened land policies in the arid West; Gifford Pinchot, Theodore Roosevelt's chief forester; ]ohn Muir, who popularized the gospel of wilderness preservation; Stephen Mather, who launched the National Park Service; and Aldo Leopold, advocate of an ethical attitude toward the land. Other chapters deal with Harold Ickes, who as Franklin D. Roosevelt's secretary of the interior spurred conservation efforts and encouraged economic recovery from the Great Depression; David Brower, the controversial executive director of the Sierra Club; and Rachel Carson and Barry Commoner, who alerted Americans to the dangers of an environment increasingly polluted by toxic chemicals.