I’ve never really been afraid of the dark, which is odd because I’m an anxious person in general and the dark is a primal fear. I’m clinically phobic of spiders, and of heights, and it turns out thanks to a good friend one summer I was able to prioritize those fears. I am more afraid of spiders than of heights. We were on a bus day-trip into Albania, to see the spectacular ruins at Butrint, curving along narrow dirt roads. This was our third such trip, so I (and she) knew I would need some literal hand-holding as I cried silently, my imagination sending us to our deaths at every turn. She narrated the landscape for me, just talking to keep me unfocused, describing the flat prairie of Iowa where we both were in school. She described the rolling farmland that surrounded us back home, and then the bizzare half-built buildings that surrounded us on the road in Albania. The driver told us that they had been built without permits, and that what happened is developers would start to build, and then the government would stop them, leaving the half-made carcasses of buildings in their wake. Many of these were not up to code, as was obvious by their tilting exposed foundations and collapsing floors and roofs. Heroic though her efforts were, she was running out of things to describe when she exclaimed in delight “Look! A spider!” I jumped in my seat, and she quickly added “It’s on the outside of the window.” But in that moment I learned something about myself that I didn’t previously know: spiders are scarier than heights.

The dark on the other hand always felt comfortable to me. Comforting. Safe. I’ve always been a night owl, and I grew up in the suburbs of Boston, in pervasively brightly-lit neighborhood. I had nothing to fear then from the dark, in fact, what I would have called the dark I know now barely qualifies as darkness at all. A teenager in Boston staying up all night there was enough ambient light in the city to read by easily. I’m not much of a nature person, and I’ve spent most of my life living in or near cities, and when I travel I travel to other cities. Like most people my age living in an industrialized country, I hadn’t ever really known the night. Until two summers ago, when we went on a week vacation to Acadia National Park in Maine.

This book talks about individual experience of the dark in terms of deprivation, of pollution, of biological necessity, of spiritual and psychological necessity, and in terms of wonder. The wonder that I felt that night in Acadia when we just happened to have been outside by firelight long enough that my eyes were more adjusted to the dark than they’ve ever been before, and I just happened to look up, and it happened that it was a clear, moonless night. It was brief, but exquisitely transformative. I’d never seen anything like it before. The Milky Way. A year later, traveling in rural Peru, we took a brief cold moment to go outside, stand around for a few minutes to let our eyes adjust, and stare up at the Southern Hemisphere view of the Milky Way. Even more impressive, even more astonishing. These are my two darkest nights. I hope to have many more.

The End of Night covers ever imaginable facet of the issue of our fleeting darkness. That we take for granted our mostly starless skies in the same way that a hundred years ago most people would have taken for granted the sight of the Milky Way, even in the city. That 90% of people growing up in the U.S. now will grow up without ever seeing the starry sky. That light is not a simple good in the world, where more means better. Light is not unambiguous. It has an ethics.

Electric light especially, but earlier forms of lighting the nights had their own ethical complications, more obvious now to a modern mind. Whale oil, for example. Not just an ethics of animal cruelty and exploitation, but also of the exploitation of humans. Or, something horrifying to my sensibilities, that Shetland Islanders would kill and store hundreds of storm pestrels  (a blubbery seabird), thread wicks down their throats, and light them on fire for a torch. Our nearly pathological fear of the dark has resulted in some gruesome acts. Especially when you consider that on most clear nights there is enough natural light for the human eye to see by. Not just from the zodiacal light, but from atmospheric reflection, and the moon much of the time.

But electric light, and the relative cheapness of energy, has a whole different set of ethical complications. There are the obvious energy ethics: only 4% of the energy used to light a lightbulb is used to make light. The rest is wasted and dissipated primarily as heat at the power source, through the transmission, and then at the light source. That it costs on the order of millions of dollars a night to light up a mid-sized city, and that money is coming from taxpayers. There are obvious ecological issues too: lights at night damage the environment in a way that is almost unimaginable because of its pervasiveness. Nocturnal animals have their biorhythms disrupted, their mating and breeding patterns altered, their feeding and migratory patterns damaged. Those are long-term issues. Short-term issues go like this: one night, in Georgia, 50,000 migrating birds followed a light at an airport (this is called “light trapped,” and its very common) and plunged straight into the ground, dying on impact.

There are also human ethics here. Electric light at night, especially blue light (the ever-increasing majority of the light we experience) is a known carcinogen. As in causes cancer. It’s also linked to increased depression, anxiety, obesity, miscarriages, and diabetes, to name just a few. The disruption of human circadian rhythms is a serious health problem, and the American Medical Association has adopted a resolution against light trespass, the primary cause of these disruptions. Most of us who live in communities (really, of any size) experience significant light disruption. But people who work the night shift experience worse. That’s about 20% of the current workforce in the U.S., and that demographic made up of a disproportionate number of women and ethnic minorities.

And what about safety? Well, actually, all the studies done on the relationship between lighting and crime show something similar: that there is no positive impact of increased brightness on crime. In some studies, the opposite has been shown: that brighter areas are more likely to have crime. The military has consulted with lighting experts, and this result has been replicated. More light is actually more dangerous, on so many levels.

This book is an absolute trove of information about light and darkness. But it’s also expertly written, extremely enjoyable to read. It engages not just with numbers and studies and explanations of the Bortle scale (which measures the darkness of the sky, 1 being the darkest), but with the idea of the dark. Artistically and culturally, spiritually and psychologically, we need the dark. And this book makes an informed and compelling case for preserving this natural resource, along with the others we are already fighting for.

(Since this is International Dark Sky Week, let me also recommend you visit darksky.org)