"In wildness is the preservation of the world," wrote Henry David Thoreau, a nineteenth-century New England writer who became a founding figure of today's environmental movement. His life and work ushered in a uniquely American perspective on nature, a philosophy that made an unprecedented defense of the value of wilderness. In so doing, he diverged dramatically from long-standing philosophical traditions that place human interests above the actions of the natural world.

Historical Roots: Running Out of Wilderness, Running Into Opposition

Thoreau (1817–1862) showed that a sense of wonder and inspiration could be found in "raw" nature, which human beings had traditionally regarded as chaotic, foreboding, or downright dangerous. He relied on personal experience, monitoring seasonal changes in the plant and animal life around him, writing accounts of his trips to the mountains and rivers of Maine, and spending extended periods of time living in a primitive cabin on Walden...