Ed Abbey is right, and I think he did a lot more productive than Thoreau, but that's Thoreau. What Cactus Ed said was:
“At some point we must draw a line across the ground of our home and our being, drive a spear into the land and say to the bulldozers, earthmovers, government and corporations, “this far and no further.” If we do not, we shall later feel, instead of pride, the regret of Thoreau, that good but overly-bookish man, who wrote, near the end of his life, “If I repent of anything it is likely to be my good behavior.”