Foreword<br > hotographs of the earth show that it has a green-blue color. The planet<br > acquired this pleasant distinction， it appears， after turning in the sun-<br >light for about three billion years. Solar energy， arriving at its surface at the<br >rate of two calories per square centimeter per minute， ignited the processes<br >of life in the primordial waters. The earth， in consequence， soon became<br >endowed with an atmosphere of approximately its present composition. For<br >about a billion and a half years the mixtures and compounds of the principal<br >constituents of the air and water--the light elements carbon， hydrogen， oxy-<br >gen and nitrogen--have been maintained in steady state by cyclic passage<br >through the tissues of plants， the animals that eat them， and the decompos-<br >ers of both. The biosphere-this thin film of air and water and soil and life<br >no deeper than ten miles， or one four-hundredth of the earth s radius--is now<br >the setting of the uncertain history of man.<br > The biosphere provides the context and perspective for consideration， in<br >this book， of the questions that are clustered in public discussion in the<br >United States today under the horizon-sweeping title of "Environment." The<br >very word has become a term of reproach， and a millenial anxiety pervades<br >the discussion. The classical Malthusian equation (in which production in-<br >creases arithmetically in the numerator and human reproduction increases<br >geometrically in the denominator) shows once again that population growth<br >must outrun the means of subsistence. The same logic argues that industrial<br >technology only hastens the despoliation of the earth s finite resources and<br >makes survival meanwhile a dubious privilege.<br > It is not enough to note the irony in the fact that such despair is charac-<br >teristically to be found among the most fortunate members of the few national<br >populations for whom the iron law of scarcity has been annulled. The mood<br >requires examination from a bigger set of premises supplied by enlargement<br >