As I got better, I wondered what I would do with the rest of my life. I went back to making a video every Tuesday and a weekly podcast with my brother, but I wasn’t writing. That fall and winter was the longest I’d gone without trying to write for an audience since I was fourteen years old. I suppose I missed writing, but in the way you miss someone you used to love.

I left Booklist and Chicago in 2005, because my wife, Sarah, got into graduate school in New York. When she finished her degree, we moved to Indianapolis, where Sarah worked for the Indianapolis Museum of Art as a curator of contemporary art. We have lived here ever since.

I read so much at Booklist that I can’t remember when I first came across the word Anthropocene, but it must have been around 2002. The Anthropocene is a proposed term for the current geologic age, in which humans have profoundly reshaped the planet and its biodiversity. Nothing is more human than aggrandizing humans, but we are a hugely powerful force on Earth in the twenty-first century.

My brother, Hank, who started out his professional life as a biochemist, once explained it to me like this: As a person, he told me, your biggest problem is other people. You are vulnerable to people, and reliant upon them. But imagine instead that you are a twenty-first-century river, or desert, or polar bear. Your biggest problem is still people. You are still vulnerable to them, and reliant upon them.

Hank had been with me on the book tour that fall of 2017, and to pass the time on long drives between cities, we’d try to one-up each other with absurd Google user reviews for the places we drove past. A user named Lucas, for example, gave Badlands National Park one star. “Not enough mountain,” he reported.

In the years since I’d been a book reviewer, everyone had become a reviewer, and everything had become a subject for reviews. The five-star scale was applied not just to books and films but to public restrooms and wedding photographers. The medication I take to treat my obsessive-compulsive disorder has more than 1,100 ratings at Drugs.com, with an average score of 3.8. A scene in the movie adaptation of my book The Fault in Our Stars was filmed on a bench in Amsterdam; that bench now has hundreds of Google reviews. (My favorite, a three-star review, reads in its entirety: “It is a bench.”)

As Hank and I marveled at the sudden everywhereness of reviewing on a five-star scale, I told him that years earlier, I’d had an idea to write a review of Canada geese.

Hank said, “The Anthropocene . . . REVIEWED.”

I’d actually written a few of the reviews back in 2014—the one about Canada geese, and also one on Diet Dr Pepper. In early 2018, I sent those reviews to Sarah and asked for her thoughts.

When I reviewed books, “I” was never in the review. I imagined myself as a disinterested observer writing from outside. My early reviews of Diet Dr Pepper and Canada geese were similarly written in the nonfictional version of third-person omniscient narration. After Sarah read them, she pointed out that in the Anthropocene, there are no disinterested observers; there are only participants. She explained that when people write reviews, they are really writing a kind of memoir—here’s what my experience was eating at this restaurant or getting my hair cut at this barbershop. I’d written 1,500 words about Diet Dr Pepper without once mentioning my abiding and deeply personal love of Diet Dr Pepper.