Environmental Research Foundation . . P.O. Box 5036, Annapolis, MD 21403 . .
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To subscribe, E-mail the words . . To maintain life, humans require a steady flow of physical materials and energy. Only nature can create all these resources. Nature's most basic process uses solar energy to convert carbon dioxide, water, and minerals into plants, the basis of all food chains. Our economy provides us with goods and services, all of which derive from the materials and energy that nature produces.