If ecology is a “subversive subject,” as Paul Sears suggests, what is it trying to subvert? Some of the possibilities that come to mind are: the accepted notion of what science does; the values and institutions of expansionary capitalism; the bias against nature in western religion. All of these were targets of the nineteenth-century Romantics; they were the first great subversives of modern times. Understanding their point of view, therefore, will contribute to our understanding of the ecology movement today. But the connection between contemporary ecology and Romanticism is even more direct than this sharing of antagonists. The Romantic approach to nature was fundamentally ecological; that is, it was concerned with relation, interdependence, and holism. Nowhere is this similarity of outlook more clearly revealed than in the writings of Henry David Thoreau (1817-1862), the nineteenth-century inheritor of Gilbert White’s arcadian legacy. Thoreau was both an active field ecologist and a philosopher whose ideas anticipated much in the mood of our time. In his life and work we find a key expression of the Romantic stance toward the earth as well as an increasingly complex and sophisticated ecological philosophy. We find in Thoreau, too, a remarkable source of inspiration and guidance for the subversive activism of the recent ecology movement.