Bill Mollison groups the earth’s resources into five categories. These resources are:
- Those which increase by modest use. For example, green browse that is uneaten by deer may become hard and unpalatable.
- Those unaffected by use. Some examples are a view or a good climate, hydroelectric power.
- Those which disappear or degrade if not used. An example is an unharvested crop of an annual.
- Those reduced by use. Some examples are a fish or game stock unwisely used, clay deposits, coal and oil.
- Those which pollute or destroy other resources if used. Examples include radioactives, super highways, large buildings.
Categories 1-3 are those most commonly produced in natural systems and rural living situations, and are the only sustainable basis of society. Categories 4 and 5 are the result of urban and industrial development, and if not used to produce permanent beneficial changes to the ecosystem, become pollutants (some are permanent pollutants in terms of the lifetimes of people).It follows that a sane society manages resources categories 1 to 4 wisely, bans the use of resource category 5, and regulates all uses to produce sustainable yield. – Permaculture: A Designer’s Manual, p.16