Those who want Heaven most

I think the idea of "going green" is a good thing. But it's important to not make it the main thing. We should be a good steward of this planet, but not in order to save it. Nature, C.S. Lewis says, is a sinking ship. He goes on to say the following in Present Concerns, in an essay entitled On Living in an Atomic Age:

“For it is part of our spiritual law never to put survival first: not even the survival of our species. We must resolutely train ourselves to feel that the survival of Man on this Earth, much more of our own nation or culture or class, is not worth having unless it can be had by honorable and merciful means.”

and

“Nothing is more likely to destroy a species or a nation than a determination to survive at all costs. Those who care for something else more than civilization are the only people by whom civilization is at all likely to be preserved. Those who want Heaven most have served Earth best. Those who love Man less than God do most for Man.”