“I would not sacrifice a single living mesquite tree for any book ever written. One square mile of living desert is worth a hundred 'great books' - and one brave deed is worth a thousand.”

“Philosophy without action is the ruin of the soul. One brave deed is worth a hundred books, a thousand theories, a million words. Now as always we need heroes. And heroines! Down with the passive and the limp.”

“What we need now are heroes and heroines, about a million of them, one brave deed is worth a thousand books. Sentiment without action is the ruin of the soul.”

“I think it is far more important to save one square mile of wilderness, anywhere, by any means, than to produce another book on the subject.”

“A man on foot, on horseback or on a bicycle will see more, feel more, enjoy more in one mile than the motorized tourists can in a hundred miles.”

“I might also say, regarding reviews and reviewers, that I have yet to read a review of any of my own books which I could not have written much better myself.”

“it will be objected that a constantly increasing population makes resistance and conservation a hopeless battle. this is true. unless a way is found to stabilize the nation's population, the parks can not be saved. or anything else worth a damn. wilderness preservation, like a hundred other good causes, will be forgotten under the overwhelming pressure of a struggle for mere survival and sanity in a completely urbanized, completely industrialized, ever more crowded environment. for my own part i would rather take my chances in a thermonuclear war than live in such a world.”