The ultimate test of a man's conscience may be his willingness to sacrifice something today for future generations whose words of thanks will not be heard.

I think the internal combustion engine will disappear from the streets of our cities in the next thirty years because transportation will be mass transportation, or probably electrical power.

Trails are relatively inexpensive. A splendid national network of all kinds of trails can be established at less cost than a few hundred miles of super highway.

It was truly an astonishing grassroots explosion, ... The objective was to get a nationwide demonstration of concern for the environment so large that it would shake the political establishment out of its lethargy.

The bigger the population gets, the more serious the problems become... We have to address the population issue. The United Nations, with the U.S. supporting it, took the position in Cairo in 1994 that every country was responsible for stabilizing its own population. It can be done. But in this country, it's phony to say 'I'm for the environment but not for limiting immigration.'

We must realize that we're all part of a web of life around the world. Anytime you extinguish a species, the consequences are serious.

Our air, water, soil, forests, oceans, rivers, lakes, scenic beauty, wildlife habitat, minerals, that is the wealth of the country.