This essay examines the transformation in land relations known as the enclosure movement that paralleled the rise of the British Empire. It reveals this transformation to be a major motivator in today's cultural and political orientations toward the environment, and toward land relations in general. It argues that the ontology of enclosure has continued to spread in the twentieth and twenty-first centuries to geographical locations formerly connected to British and European colonial expansion, adversely affecting the struggles of today's agricultural communities. The major manifestation of the enclosing ontology appears in the trope of “energy security,” a term meant to justify the enclosure of third world agricultural spaces for the future development of presumably green-friendly plant alternatives to oil. The essay also explores the activities of the Brazilian Landless Workers' Movement (MST) and its alternative relationship to the land. It concludes with an admonitory statement about the future viability of the geopolitics of enclosure.