"The labor of nature is paid, not because she does much, but because she does little. In proportion as she becomes niggardly in her gifts, she exacts a greater price for her work. Where she is munificently benefi­ cent, she always works gratis." David Ricardo * This book interprets nature and the environment as a scarce resource. Whereas in the past people lived in a paradise of environmental superabundance, at pre­ sent environmental goods and services are no longer in ample supply. The envi­ ronment fulfills many functions for the economy: it serves as a public-con­ sumption good, as a provider of natural resources, and as receptacle of waste.