Earth Matters examines the relationships between alternative religion in North America and the natural world through the twin lenses of the history of religions and cultural anthropology. Throughout, nature remains a contested ground, defined simultaneously the limits of cultural activity and by an increasing expansion of claims to knowledge by scientific discourses. Less a historical review than a series of fugues of thought, Earth Matters engages with figures like the French vitalist, Georges Canguilhem, the American environmentalist, John Muir; the founder of Deep Ecology, Arne Næss; the collaborators on Gaia Theory, James Lovelock and Lynn Margulis; the physicist and New Age scientist, Fritjof Capra; and the Wiccan writer and activist, Starhawk. These subjects move in spirals throughout the thesis: Canguilhem opens the question of vitalism, the search for a source of being beyond the explanations of the emerging sciences. As rationalism expands its dominance across the scientific landscape, this animating force moves into the natural world, to that protean space between the city and the wild and in the environmental thinkers who initially moved along those boundaries. As the twentieth century moves towards a close, mechanistic thinking simultaneously reaches heights of success previously unimagined and collapses under the demand for complexity posed by quantum physics, by research in genetic interactions, by the continued elusive relationship of mind to health. This allows the wild to return inside through the internalization of consciousness sparked by the American New Age, but also provides a new model to understand the natural world as complex zone open to a wide variety of strategies, including the multiplicities of understanding offered through contemporary neopaganisms. Earth Matters argues for the necessity of the notion of ecology, both as an environmental concern but also as an organizing principle for human thought and behavior. Ecologies are by their nature complex and multi-variegated things dependent upon the surprising and unpredictable interaction of radically different organisms, and it is through this model that we are best able to understand not only ourselves but also our communities and our efforts to make sense of the external world.