Said in reference to the Grand Canyon, but an apt blanket statement for wilderness in general:

In the Grand Canyon, Arizona has a natural wonder which is in kind absolutely unparalleled throughout the rest of the world. I want to ask you to keep this great wonder of nature as it now is. I hope you will not have a building of any kind, not a summer cottage, a hotel or anything else, to mar the wonderful grandeur, the sublimity, the great loneliness and beauty of the canyon. Leave it as it is. You cannot improve on it. The ages have been at work on it, and man can only mar it.

-Theodore Roosevelt

I was watching an IMAX documentary called Coral Reef Adventure tonight and one of the divers said something I think is pretty profound:

We do not inherit the world from our parents, we are borrowing it from our children.

That small difference in outlook can make a huge impact on how we decide to treat this planet.