Billions & Billions, pg. 80

“But we humans are newcomers, arising only a few million years ago. Our present technical civilization is just a few hundred years old. We have not had much recent experience in voluntary interspecies (or even intraspecies) cooperation. We are very devoted to the short-term and hardly ever think about the long-term. There is no guarantee that we will be wise enough to understand our planetwide closed ecological system, or to modify our behavior in accord with that understanding.”

– Carl Sagan, Billions & Billions, pg. 80