We have become great because of the lavish use of our resources, and we have just reason to be proud of our growth. But the time has come to inquire seriously what will happen when our forests are gone; when the coal, the iron, the oil, and the gas are exhausted; when the soils shall have been still further impoverished, and washed into the streams, polluting the rivers, denuding the fields, and obstructing navigation.

-Theodore Roosevelt (on the merits of public lands)