Our societal reference point for passionate environmentalism is sometimes tinged with images of tie-dyed tree huggers chaining themselves to ancient trunks. While there's certainly room to appreciate that sort of vigor, we at Big Think prefer a little more nuance in our environmentalists.

Take, for instance, the great Scottish-American environmentalist John Muir (1838-1914), best known for his journeys (and subsequent writings) of the American west coast. Here are some Earth Day words of wisdom from Muir, excerpted from his 1901 book Our Natural Parks:

"The battle we have fought, and are still fighting, for the forests is a part of the eternal conflict between right and wrong, and we cannot expect to see the end of it. ... So we must count on watching and striving for these trees, and should always be glad to find anything so surely good and noble to strive for."