I woke, shaken from the dream. It was not quite dawn but that filtered darkness just as the first light shadows the curtains. It had been a dream of words, of many people, their voices, and my sense of a great conversation woven with musical phrases. But all I could remember, even just waking, was one phrase. It was clear. Thus runs the world away. It was uttered in closure with a shake of the head, a sorrow in the speaker’s voice, conclusive.

Later that morning I remembered it again, though I misremembered the source. Macbeth, I thought, but a quick search took me instead to Hamlet. Of course it was Hamlet, in one of his rhymed quatrains; in fact, Hamlet may be recycling part of an older folksong, a bit of lore in hymnal meter, as he speaks to Horatio, in the middle of Act III, which is in the middle of the play.

It’s July 30, 2017, as I start taking notes for the present introduction to “Nature’s (Human) Nature.” It is December 1, 2017, when I finish. Four months. During this time, with more than 350 thousand births each day, according to the US Census Bureau, and about half as many deaths, we have added twenty-eight million human beings, give or take, to our gasping planet. That’s about eighty-four million people in the past year. By another count we have added, in the one year since our last “Nature’s Nature” feature, between seventy-five million and eighty-five million more of us. In fact, I have compared many sources—from the World Bank to Wikipedia, the US Census Bureau to the United Nations—and while no statistic is quite the same as another, the ballpark average is sufficient for my purposes here.

Let’s add another fact. The United Nations reports that more than 55 percent of the current human global population now lives in urban areas. Once upon a time we emerged from the waters and slowly moved into the savannahs and trees. Now we see the arable lands rapidly shrinking, the farm-fields imperiled, and waterways poisoned. If we are growing and spreading—like a virus, as we say—our world’s kindred species are growing extinct at a rate between one thousand and ten thousand times the “natural” background rate. Still, deep in our imaginations—far back in our prehuman memories—resides that primordial landscape, that natural scene and setting made of wilderness, wildness: nature. Is it nostalgia or sentimentality that impels our nature poetry now? Is it a primal, abiding sense of home and habitat? Is it the poets’ collective warning that makes us write about the trees, birds, and icecaps, in a stark jeremiad of dread and shame?