The World Resources Institute did a study on the amount of natural resources used to produce the total GNP for the United States. What it found was that as time goes by US producers used less resources for the same output than the year before. And the US doesn't even have a particularly good record when it comes to energy consumption. The Japanese use half as much as the US does to produce the same amount of goods. One example Sagoff uses to illustrate our ability to make more with less is that of the toy manufacturer Saga which produced a child's hand-held game called Saturn.
Humans learn and improve on what each proceeding generation has done.
The desire to earn a profit in a competitive market rewards entrepreneurs who figure out new methods to increase productivity. The result is that each year we learn how to use the resources we have more efficiently. Driven by the selfish desire to earn higher profits these entrepreneurs make all of us wealthier in the long term. More efficient use means less pollution but it also means higher profits. And he was right.