There is much talk of "sustainability" these days, but I don't think very many people have considered what that truly means. "Sustainable" has become synonymous with "green", which in our hyper-consumerist American society has transformed into "buy something". Understandable, perhaps, but it's deadly wrong. The World English dictionary defines "sustainable" as "2. (of economic development, energy sources, etc) capable of being maintained at a steady level without exhausting natural resources or causing severe ecological damage", which seems to me to be a pretty good definition of what the word really means, as opposed to what people think it means.