Professors Rees and Wackernagel have developed a new concept to assess individuals and countries impact on the environment, a quantitative measure which acts as a common denomintor for all peoples, at all levels of affluence or poverty. This will become the yardstick of our future, like the invention of money by the Babylonians or Assyrians has become the unit of exchange in the trade of goods and services. Clearly written, the book is needed to be understood by all politicians, bankers, voters, leaders and living humans. Knowing ideas such as these is crucial and essential for our survival in the biosphere.