building in a potential green economy. Natural materials tend to be those close at hand, and they are therefore dependent on the specific building situation. Many owner-builders may have ready access to timber and stone, and ways to utilize them in an ecological fashion. In timber-framing and stone masonry, humanity also has a vast reservoir of craft knowledge and experience, which is as much a spiritual resource as a material one. Stone and wood are almost primordial substances as far as the human experience goes, and one should not underestimate the importance of preserving, and even extending, our knowledge of them.