Sustainability has come into its own in the popular press within the last five years as a subject of discussion and matter of concern. A number of writers have given its definition and application serious thought.

At the most succinct level, Robert Thayer defines sustainability as "a characteristic of a process or state that can be maintained indefinitely."(Gray World, Green Heart, 1994, pg. 99) Lester R. Brown, Founder and President of Worldwatch Institute says, "a sustainable society is one which satisfies its needs without diminishing the prospects of future generations."

This use of social consciousness -- future generations -- as a measure appears in several sources as a theme. Robert Gilman, Director of the Context Institute applies it to his definition. "Sustainability is equity over time." "As a value, it refers to giving equal weight in your decisions to the future as well as the present. You might think of it as extending the Golden Rule through time, so that you do unto future generations (as well as to your present fellow beings) as you would have them do unto you." David McCloskey, Professor of Sociology at Seattle University, has this to add. "Actions are sustainable if: 1) There is a balance between resources used and resources regenerated.
2) Resources are as clean or cleaner at end use as at beginning. 3) The viability, integrity, and diversity of natural systems are restored and maintained. 4) They lead to enhanced local and regional self-reliance. 5) They help create and maintain community and a culture of place. 6) Each generation preserves the legacies of future generations."

Other writers help us put the sustainability of human settlements into their larger natural context. David Orr (Ecological Literacy, 1992) finds sustainability to be "...the set of perceptual and analytic abilities, ecological wisdom, and practical wherewithal essential to making things that fit in a world of microbes, plants, animals, and entropy. In other words, (sustainable design) is the careful meshing of human purposes with the larger patterns and flows of the natural world, and careful study of those patterns and flows to inform human purposes.

The idea that sustainability is not a static condition is emphasized. Kenneth Boulding, economist and futurist, brings this out when he states, "The concept of sustainability does not really refer to some equilibrium state, not even the stationary state of classical economists, but to a sustainable evolutionary process of continuous change...We certainly don't want the existing world structure to be sustainable. We want to improve it." Dr. Karl Henrik-Robert, MD, founder of The Natural Step in Sweden reinforces this idea. "A transition to sustainability involves moving from linear to cyclical processes and technologies. The only processes we can rely on indefinitely are cyclical; all linear processes must eventually come to an end."

Sustainability as a concept must be moved into action as proposed by Steve Nicholas, Department of Planning, City of Seattle. "Sustainable describes actions, policies, programs, etc., -- by individuals, groups, corporations, or government entities -- that could be adopted by all such individuals, groups, corporations, or government entities with out eventually destroying the requisite resources, or resulting in gross inequities among people."

Robert Thayer (Gray World, Green Heart, 1994, pg. 100) offers some additional definitions of activities with the 'sustainable' modifier: 1) "Sustainable Development: Improving the quality of human life while living within the carrying capacity of supporting ecosystems." 2) "Sustainable Use: Use of an organism, ecosystem, or other renewable resource at a rate within its carrying capacity for renewal. Carrying capacity is capacity of an ecosystem to support healthy organisms while maintaining its productivity, adaptability, and capability for renewal."
3) "Sustainable Landscape: A place where human communities, resource uses, and the carrying capacities of surrounding ecosystems can all be perpetually maintained." and 4) "Sustainable Technology: A technology which, when employed productively by humans, results in no loss of ecosystem carrying capacity, resource availability, or cultural integrity."

Sustainability is not a new concept to permaculture. In fact, permaculturists have been practicing sustainability and developing approaches to its accomplishment for years. It has many lessons to provide to others.