To achieve true sustainability, we must reduce our 'garbage index" - that which we permanently throw away into the environment that will not be naturally recycled for reuse - to near zero. Productive activities must be organized as closed systems. Minerals and other nonbiodegradable resources, once taken from the ground, must become a part of society's permanent capital stock and be recycled in perpetuity. Organic materials may be disposed into the natural ecosystems, but only in ways that assure that they are absorbed back into the natural production system. - David C. Korten