voluntary simplicity, mind-body awareness, vernacular design, and co-operative development. The natural building movement is, for this reason, both the countercultural soul of green building and a significant part of its technological cutting-edge. It may represent a comparatively small portion of green building today, but its direct and imaginative approaches make it central to the evolution of building. As I will show, most of these techniquesold or neware not purist in attempting to avoid industrial components or machinery. There is a healthy respect for many elements of mass production, modern science and various kinds of construction tools. But there is also a great respect for craft and for many traditional building methods and materials that were violently pushed aside by the industrial revolution. The industrial revolution coincided not only with a more specialized division of labour, but with an massive centralization and concentration of energymuch of which was considered as free and not tabulated by the accountants ledger. The extraction, processing and refining of industrial materials is energy-intensive, making the embodied energy and ecological rucksack of commercial building materials relatively high. Natural building is an expression of the maturation of the green building movement, from its initial preoccupation with a buildings operating energy-efficiency to newer concerns with embodied energy. The concept of embodied energy is, in fact, probably the core technical concern of natural building. But natural buildings concernsmore than any area of green buildinggo well beyond the technical to the social and spiritual.