"A thousand years ago this wouldn’t have been the case. If human beings had suddenly vanished a thousand years ago, the planet would have healed overnight with no damage. Maybe a few lumps where the pyramids stand. One hundred years ago—or even fifty years ago—the world would have healed itself just fine in the absence of people. But not now. We crossed the line. The only thing that can keep the planet turning smoothly now is human free will forged into effort. Nothing else. That’s why the world has seemed so large in the past few years, and time so screwy. It’s because Earth is now totally ours."