The hawk sat on a limb three feet above my head and did not stir as I walked under—that was the first sign.

I’d been off hiking for about a week, a long solo backpack through my home mountains, the Adirondacks of upstate New York. The first few days out I might as well have been back in my room—I strode purposefully along the trail, eyes fixed on that focusless middle-distance that you stare at when you drive. My mind chattered happily away—my own little CNN delivering an around-the-clock broadcast of ideas, plans, opinions: What was I going to work on next? Who would win the presidential election? What were some neat things I could buy? My mind was buzzing, following all its usual tracks though I was deep in the woods.

The days wore on. The imposed input lessened—no radio, no paper, no conversation. I could feel the chatter in my head begin to subside. Either the peace of the forest was beginning to penetrate, or the stocks of mental junk food were starting to dwindle; whatever the cause, the buzz turned to hum, and once in a while to quiet.

And so I was not completely surprised when the hawk kept his perch, or a few minutes later when I passed a pair of grazing deer and they merely looked up a moment, didn’t spook. I was still wearing the rustling fluorescent uniform of the modern hiker, but I’d begun, perhaps, to give off fewer, calmer vibrations.

I’d been walking through rain for days; it had long since penetrated my Gore-Tex hide, and so that afternoon when the sun finally came out I made an early camp by the lake. I hung out my clothes in the branches to warm; held my white and wrinkled feet up to the sky to toast; unfolded in the lovely heat like a snake on a stone. Soon a band of merganser chicks, trailing their mother, circled the small cove by which I lay, paying no attention to me. My aura of invisibility lasted all day, soothing one creature after another, until I was feeling part creature myself. Naked, hidden by the fringe of birch leaves, I watched canoeists paddle chattily by, and they seemed nearly to belong to another race. That night I was aware of every second of the endless sunset: the first long rays of the sun as the afternoon turned late, the long twilight, the turn of the sky from blue to blue to blue to—just as it turned black, a heron came stalking through my tiny cove, standing silently and then spearing with a sudden spasm; I couldn’t see her, not really, but I knew where she was. The sky darkened, the stars in this dark place spread across the sky bright and insistent. We were unimaginably small, this heron and I, and extremely right.

I tell this memory—one of my happiest—as a way of plunging into that great sea called Walden. Understanding the whole of this book is a hopeless task. Its writing resembles nothing so much as Scripture; ideas are condensed to epigrams, four or five to a paragraph. Its magic density yields dozens of different readings—psychological, spiritual, literary, political, cultural. To my mind, though, at the beginning of the twenty-first century, it is most crucial to read Walden as a practical environmentalist’s volume, and to search for Thoreau’s heirs among those trying to change our relation to the planet. We need to understand that when Thoreau sat in the dooryard of his cabin “from sunrise till noon, rapt in a revery, amidst the pines and hickories and sumachs, in undisturbed solitude and stillness, while the birds sang around or flitted noiseless through the house,” he was offering counsel and example exactly suited for our perilous moment in time.

He had, of course, no idea that he was doing so.

Although he wrote often about the natural world, Thoreau lived at the very onset of the industrial age, and so knew nothing about parts-per-million, or carcinogenesis, or chlorofluorocarbons. One reads him in vain for descriptions of smog. Mass extinction seems unthinkable—instead, he is gratified and reassured by the profligacy of the living world: “I love to see that Nature is so rife with life that myriads can afford to be sacrificed and suffered to prey on one another, that tender organizations can be so serenely squashed out of existence like pulp—tadpoles which herons gobble up, and tortoises and toads run over in the road.” His world was not used up, suffering—he was in the sixth party of white people to climb Maine’s Mt. Katahdin, on an expedition that took him through the heart of that then-mighty wilderness. And though he could perhaps foresee the ruination that greed might cause (the East would soon be logged so bare that “every man would have to grow whiskers to hide its nakedness”), he had no inkling that we could damage the ozone or change the very climate with our great consumer flatulence. “Thank God the sky is safe,” he wrote.

Furthermore, even if Thoreau had realized the challenges facing the modern environment, there’s no good reason to think he would have pitched in to help. Reformers, he writes, “are the greatest bores of all,” and I doubt a few hundred fundraising appeals from the Audubon Society would have changed his estimation that he’d received but one or two letters “that were worth the postage.” More crucially, he was aggressively uninterested in the prospect of community that sage environmentalists now hold out as our great chance for salvation. The prospect of, say, abiding more closely with his fellows so that they could pool resources, live more efficiently, take pleasure in rubbing shoulders would not have appealed to a man who thought “the old have no very important advice to give to the young,” who considered that two people ought not to travel together, who found it “wholesome to be alone the greater part of the time.” Were Thoreau a modern third-grader, his report card would doubtless note his lack of social skills; it is no accident that he never married, and to imagine him with a child is a joke. There is a great deal he can’t teach us.

You could even lay at his door, I think, some particular environmental problems. In his day, much to his disgust, people clustered together in Concord town and ventured out to Walden to cut ice; partly under his intoxicating influence, many many more of us have come to make our homes on the lake and ocean shores, in the scenic spots, far from the places where we work. There’s hardly an unprotected shoreline in the lower forty-eight not lined with cottages and cabins; wilderness is now a selling point for the enterprising realtor. Even the suburb owes something to him; though clearly a corruption of his vision, in its splendid isolation the subdivision colonial retains a bit of his rude cabin.

So to call him an environmental prophet—in many ways the environmental prophet, a writer of the highest value to the twenty-first century—requires that we think more deeply about what it might mean to live an environmentally sane life. It means recognizing the precise nature of the problems that we face. If those questions are technical, then he is of no help. If our largest environmental problems are the result of something going wrong, some pollutant spewing unchecked from smokestack or exhaust pipe, then he’s simply an interesting historical curiosity. Confronted with a smoggy city, I’d choose a catalytic converter over a pocket copy of Walden. And indeed we’ve nearly solved smog no thanks to Henry David. New equipment scrubs carbon monoxide from the exhaust stream of your car, which is why Los Angeles is cleaner now than a generation ago. New filters on factory pipes clean up rivers and lakes—that’s why fish again swim in Lake Erie.

But what if those are not the largest environmental problems we face? What if we’re really in trouble because things are going right, just at much too high a level? Consider the tailpipe of the car once more. It’s not just carbon monoxide that comes spewing out, it’s also carbon dioxide, carbon with two oxygen atoms. And this time there’s no filter you can stick on the car to cut that CO2; it’s the inevitable byproduct any time you burn fossil fuels. It also turns out that carbon dioxide represents an even greater threat than smog: its molecular structure traps heat near the planet, triggering climate change. The sky’s not safe after all; the sky is heating up. And the answer has defied the technologists. They’ve managed to double the fuel efficiency of our cars in the last forty-five years, but we’ve doubled the number of cars, and the miles they drive, spewing out ever larger clouds of CO2. Scientists tell us they can see the extra heat, watch it melt glaciers and raise sea levels. To prevent it getting worse won’t require some technical change; it will require doing with less, living more lightly. Our other biggest problems—overpopulation, habitat destruction, and so on—present the same challenge: they’re inevitable if we keep living the way we do, thinking our same thoughts.

And it is here that Thoreau comes to the rescue. He posed the two intensely practical questions that must come to dominate this age if we’re to make those changes: How much is enough? and How do I know what I want? For him, I repeat, those were not environmental questions; they were not even practical questions, exactly. If you could answer them you might improve your own life, but that was the extent of his concern. He could not guess about the greenhouse effect. Instead, he was the American avatar in a long line that stretches back at least to Buddha, the line that runs straight through Jesus and St. Francis and a hundred other cranks and gurus. Simplicity, calmness, quiet—these were the preconditions for a moral life, a true life, a philosophic life. “In proportion as he simplifies his life . . . he will live with the license of a higher order of beings.” Thoreau believed in the same intense self-examination as any cross-legged wispy-bearded Nepalese ascetic.

Happily, though, he went about it in very American ways—he was Buddha with a receipt from the hardware store. And it is that prosaic streak that makes him indispensable now.

In the advanced consumer society in which we live, How much is enough? is the first of Thoreau’s questions that we must take up, the most deeply subversive question you can currently pose. We’ve been carefully trained to know that the answer is always: More. Once, researching a book, I taped everything that came across the world’s largest cable TV system for a single day. I took my 2,400 hours of videotape home and spent a year watching it, bathed in the constant message that I needed so much. How much? Here’s a commercial for Rubbermaid. “From the day I was born,” a lady is saying, “I collected so much stuff.” (The picture shows a sad family, hemmed in by their possessions.) “So we stowed our stuff in stuff from Rubbermaid.” (Now the house is bare, save for big plastic boxes full of gear.) “Then we were so unstuffed—Hey! We need more stuff!” (Family charges happily out the door, waving hands in air.)

Thoreau begins at the beginning. He starts with Food, Shelter, Clothing, and Fuel. At the latitude of Concord, anyway, these have become “from long use . . . so important to human life that few, if any, whether from savageness, or poverty, or philosophy ever attempt to do without.” But of course each of these can be either simply or expensively obtained. He considers the possibility, for instance, of living in one of the tool crates that the railroads erect at regular intervals along the track. With a few auger holes bored for air, this did not seem “by any means a despicable alternative.” As we know, however, he opts for something a little larger—the one-room cabin that he built from timbers recycled from the shanty of James Collins. He dug a cellar in two hours’ time (Walter Harding, in his exhaustive edition of Walden, cites a study indicating that he moved 194.25 cubic feet of sand in this span, weighing 9.7 tons), then built a chimney, cut some shingles, bought secondhand windows, and eventually completed his home for twenty-eight dollars and twelve and a half cents. This was a useful exercise. Building a house involves remembering that it’s designed to fulfill a function—to shield you from the rain and snow, to enclose a volume of air that can be heated to keep you warm, to give you room for those possessions you actually need.

In Thoreau’s case, that list included a table, which doubled as a desk, a chair, and a bed. It didn’t include a closet, because the object of clothing is “first, to retain the vital heat, and secondly, in this state of society, to cover nakedness,” and furthermore “every day our garments become more assimilated to ourselves, receiving the impress of the wearer’s character, until we hesitate to lay them aside.” In other words, he wore pretty much the same clothes all the time. There was no pantry to speak of; he subsisted largely on his beloved Indian meal, his rice and rye, his beans, his occasional visits to the homes of his friends, and a woodchuck which was eating his garden. In material terms, he was on a par with many of the poorest people around the world today. And he was like them in being a good, if unconscious, environmentalist. If you are worried about the largest problems, such as global warming, then to consume only a bit is the best remedy; according to one recent calculation, by Charles Hall of Syracuse University, a dollar or its equivalent spent anywhere around the world results on average in half a liter of petroleum being burned—to manufacture the item, and carry it to you, and advertise it, and dispose of it later.

Thoreau chose his deprivation—embraced it, in fact, in the name of simplicity, philosophy, truth, so that it was not deprivation at all. And his heirs, I think, even more than the nature essayists who usually win the title, are that growing band of simplifiers whose books and seminars attract a small but significant portion of a population that has begun to feel materially satiated and desire something else. The best of these books is probably still Your Money or Your Life, by Joe Dominguez and Vicki Robin, which has sold half a million copies even though the authors recommend checking it out of the library. They are unlike Thoreau in many ways; they seem to enjoy working with other people, for instance, and they write with a prosaic clarity that would make him wince. But their books take much from his example.

Thoreau did not have contempt for money—it intrigued him, as his endless careful accounts suggest. But he realized instinctively the lesson that few of us ever learn, which is that there are two ways to get by in the world. The first is to increase income; the second is to reduce expenses. He went further than most of us will ever be willing to go, especially in his nonchalance about future security (“what danger is there if you don’t think of any?”), but there are now millions of Americans pursuing some kind of “voluntary simplicity”; they retain much of his radicalism, only in a more palatable form. And they play to an interested audience. Just as Thoreau reports constant visits from “doctors, lawyers, uneasy housekeepers who pried into my cupboard and bed when I was out,” so the pollsters report that even today many of us remain attracted to some simpler alternative. When the Merck Family Fund sponsored a survey of attitudes on consumerism in 1995 (the last year it conducted the survey), 82 percent of Americans agreed that most of us buy and consume far more than we need, and 86 percent said our children were “too focused on buying and consuming things.” Since shortly after World War II, the Gallup pollsters have inquired each year about whether or not Americans are satisfied with their lives. In 1955 the number who were very satisfied hit 35 percent. Despite the vast gains in material status in the subsequent four decades (only a tiny percentage of Americans owned a dishwasher in 1955; the microwave hadn’t been invented), the number of people who identified themselves as “very satisfied” slipped to 30 percent by 2000. It’s as if the twentieth century served as a large-scale experiment to confirm Thoreau’s hypothesis.

But if that is so—if the mass of us are at least dimly aware of our lives of quiet desperation—then why do we do so little to change? Some of the reasons are structural. The Economy exerts powerful gravity; for many people, it’s hard to escape its demands, be they medical insurance, rent, food on the table. A low-wage job and a child constrain your choices, as do student loans.

This remains an affluent nation, however, by any historical or geographical standard, a place where most people possess real options. So why do we not, by and large, take more advantage of them? I think because of the second question that Thoreau raises, this one equally well timed for the end of this century. If “How much is enough?” is the subversive question for the consumer society, “How can I hear my own heart?” is the key assault on the Information Age. How do I know what I want? What is my true desire?

To understand Thoreau’s genius, remember that he raised this question in a time and place that would seem to us almost unbelievably silent. The communications revolution had barely begun. Advertising had not yet been invented, but the few shop signs in Concord, which we would preserve as quaint markers of a vanished age, appeared already to Thoreau as billboards “hung out on all sides to allure him; some to catch him by the appetite, as the tavern and victualling cellar; some by the fancy, as the dry goods store and the jeweller’s; and others by the hair or the feet or the skirts, as the barber, the shoemaker, or the tailor.” No Internet, no television, no radio, no telephone, no phonograph; and yet somehow he sensed all that this would mean to us. He did not need to see someone babbling into a cell phone as he walked down the street to sense that we’d gone too far; he was such a hypersensitive, such an alert antenna, that he was worried before Alexander Graham Bell was born. “We are in great haste to construct a magnetic telegraph from Maine to Texas,” he writes. “But Maine and Texas, it may be, have nothing important to communicate. Either is in such a predicament as the man who was earnest to be introduced to a distinguished deaf woman, but when he was presented, and one end of her ear trumpet was put into his hand, had nothing to say.” Emerson rushed back from a summer in the Adirondack woods when he heard the great news that the trans-Atlantic telegraph cable had at last been laid; Thoreau wrote “perchance the first news that will leak through into the broad, flapping American ear will be that the Princess Adelaide has the whooping cough.”

Most of us still believe—with yellow-eyed ferocity—in the goddess Information. We want data, we want connections; we want email. We are all the Emperor in his finery, and Thoreau is nearly alone in his calm assurance that he could do without the post office, that “if we read of one man robbed, or murdered, or killed by accident, or one house burned, or one vessel wrecked, or one steamboat blown up, or one cow run over on the Western Railroad, or one mad dog killed, or one lot of grasshoppers in the winter—we never need read of another. One is enough.” Even in his day, “hardly a man takes a half hour’s nap after dinner, but when he wakes he holds up his head and asks, ‘What’s the news?’ ” He would not be shocked by MSNBC.

It’s not that he’s in favor of ignorance or self-absorption. He was well read, politically committed enough to have engaged in Civil Disobedience, and obviously steeped in the minutest changes in the world around him (the precise quality of the ice, the texture of the mud). But he understood the danger of the big Hum—both the constant barrage of chatter from the world (two, three, four hours of television a day) and its lingering echoes. Even when you turn the set off, even when you hike deep into the Adirondack woods, your mind keeps up a constant vibration, playing and replaying words and images and ideas so that you hardly notice your surroundings. So that you rarely notice your thoughts.

Try disconnecting for a while and see what the hum has done to you, see what it’s made of you. Thoreau liked his small library of books, but he recognized the danger even there: “while we are confined to books . . . we are in danger of forgetting the language which all things and events speak without metaphor.” Often, he says, he laid aside his books and even his gardening. “There were times when I could not afford to sacrifice the bloom of the present moment to any work, whether of head or hands.” He would merely sit in his door and the hours would somehow pass. Try this—see if you’re still made for musing. How long can you watch a sunset before you get bored? How long can you look at the night sky before you seek some entertainment?

The idea that we know what we want is palpably false. We’ve been suckled since birth on an endless elaboration of consumer fantasies, so that it is nearly hopeless for us to figure out what is our and what is the enchanter’s suggestion. And we keep that spell alive every time we turn on the radio or the television or the net. Because when someone is whispering something in your ear, there’s no way to think your own thoughts or feel your own responses. The signals that your heart sends you are constant, perhaps, but they’re also low and rumbling and easily jammed by the noise and static of the civilization we’ve lately built. That’s why Thoreau had to run away for a while, and it’s why another small but growing number of people are beginning to question some of the premises of our Information Age. For example, a group called TV-Free America has been organizing nationwide “Screen-Free Weeks” throughout schools since 1995; since then, millions of youngsters have turned off the tube for a week, and perhaps some few of them glimpsed the huge pleasure that comes from hearing your own true voice.

This is an environmental problem not only because the main function of the Information Revolution is to sell us stuff we don’t need, stuff that gives off carbon dioxide or gathers in dumps. It’s a problem most of all because it confuses us as to our place in the scheme of things. Without silence, solitude, darkness, how can we come to any sense of our true size, our actual relationship with the rest of the world? Some years ago I took a group of kids from the local high school for a camping trip. We live in a remote wilderness town, where no city lights blur the view of the sky. And it was the night of the new moon, so the heavens were an absolute velvet black, studded with stars. But as we were looking up and talking, it became clear that two-thirds of the kids had never been shown the Milky Way, that most potent symbol of our own true dimension. They’d been inside watching the other stars on television, the ones that insist that each of us is so central that the world orbits around us.

What nature provides is scale and context, ways to figure out who and how big we are and what we want. It provides silence, solitude, darkness: the rarest commodities we know. It provides reality, in place of the endless electronic mirages and illusions that we consider the miracle of our moment. “There is a solid bottom every where,” Thoreau insists—and it is this insistence that gets him in trouble with so many academics, committed to the postmodern notion that all is idea, stance, mutable. You cannot believe that if you have spent enough time out of doors.

“Let us spend one day as deliberately as Nature, and not be thrown off the track by every nutshell and mosquito’s wing that falls on the rails,” writes Thoreau. “Let us settle ourselves, and work and wedge our feet downward through the mud and slush of opinion, and prejudice, and tradition, and delusion, and appearance . . . till we come to a hard bottom and rocks in place, which we can call reality, and say, This is, and no mistake.” Only when we have some of that granite to stand on, that firm identity rooted in the reality of the world, only then can we distinguish between the things we’re supposed to want and the things we actually do want—only then can we begin the process of satisfying “non-material needs in non-material ways,” which environmentalist Donella Meadows has identified as our chief hope. Only then can we say “How much is enough?” and have some hope of really knowing.

In the 160 years since Walden, Thoreau has become ever more celebrated in theory, and ever more ignored in practice. “Men think that it is essential that the Nation have commerce, and export ice, and talk through a telegraph, and ride thirty miles an hour,” he writes. How sleepy that protest sounds to an age that thinks we must travel supersonically, communicate instantaneously, trade globally. Each week in our world, as many as two billion people—twice as many people as lived on the planet in Thoreau’s time—can watch the TV program Big Brother. Literally, consumption has become national policy—in the days after 9/11, the president’s main (and obscure) advice was that all good patriots should get out there and shop.

And yet the battle could still swing; we live at a pivot in history when, quite suddenly, ideas like Thoreau’s might suddenly flourish. To understand why, remember something I said earlier. He is the American incarnation in a line of crackpots and gurus from Buddha on. Jesus, St. Francis, Gandhi, and the holy men and women of every branch of the ethical religious tradition share an outlook: Simplicity is good for the soul, for the right relation with God. In the Christian formulation: Do not lay up treasure here on earth; you can’t serve both God and money; give away all that you have and follow me. Except, occasionally, for clerics and monks and saints, these are not injunctions we’ve tried very hard to put into practice.

We’ve adopted the competing religious worldview, the one that worships an ever-growing Economy. But such spiritual notions have not disappeared, either; they’ve flowed like a small but steady river through world history, never completely drying up. Thoreau helped add a new tributary to that stream. His nature writing is raw, wild, and haunting. He comes to the marsh at night to hear the hooting owls: “All day the sun has shone on the surface of some savage swamp, where the single spruce stands hung with usnea lichens, and small hawks circulate above, and the chicadee lisps amid the evergreens, and the partridge and the rabbit skulk beneath; but now a more dismal and fitting day dawns, and a different race of creatures awakes to express the meaning of Nature there.” In his wildness he harks back to the ancient pantheistic traditions, older by far than the Buddha and still alive in remnant form among some native peoples, traditions that might have understood his eagerness to eat a woodchuck raw. And he presaged the twentieth-century, American-led boom in his affection for nature. When he wrote, most of the civilized world still regarded the forest and the mountain with distaste; but in his wake came Whitman, Burroughs, Muir, and a thousand other writers, and right behind them came a million people toting backpacks. If the lakeshore cottage colony and the backcountry subdivision can be numbered among his legacies, so can the national parks and wildernesses. This stream grew larger; the concern for right relation with God joined with love of the physical world. It was still not large enough to jump its banks and flood the city where Economy sat enthroned, but more and more people could hear the roar of its rapids.

Now, quite suddenly, at the beginning of the twenty-first century, a whole new tributary of thought swells that countercultural river. The saints in their robes and the nature lovers in their Gore-Tex jackets are suddenly joined by men and women in lab coats, clutching computer printouts. The students of the largest environmental changes taking place around us come with a message eerily similar to those we’ve heard before. When the International Panel on Climate Change reported recently that humans were likely to raise the earth’s temperature 3.5 degrees this century, that they had begun to alter the most basic forces of the planet’s surface, the implication of their graphs and charts and data sets was, Simplify, simplify. Not because it’s good for your relationship with God, but because if you don’t, the temperature of the planet will be higher by 2100 than it’s been for hundreds of millions of years, which means crop- withering heat waves, daunting hurricanes, rising seas, dying forests. They were calling for community, not because it’s good for the soul but because without it there’s little chance we’ll become efficient enough in our use of energy or materials. The math is hard to argue with; business as usual and growth as usual spell an end to the world as usual. This is the one overwhelming fact of our lifetimes.

And so this river rises, gathers new freshets, drains ever more valleys. Perhaps it is nearly ready to flood our joint consciousness, to submerge our current idols, to cut a new channel for us in some as-yet-unseen direction.

But if—to paddle a little further along this metaphor—this new Concord or Merrimack really is swelling with runoff from every direction, we must take care that it is not polluted by fear. Though we need to understand and feel the depth of our dilemma, panic will only make it harder for us to simplify, to retreat from our fortresses of wealth, to back off. Thoreau understood this; his overpowering confidence, in himself and in the world, rings through every page of Walden. One day, feeling an uncustomary melancholy, he sat in his house during a rain. “I was suddenly sensible of such sweet and beneficent society in Nature, in the very pattering of the drops, and in every sound and sight around my house, an infinite and unaccountable friendliness all at once like an atmosphere sustaining me.” That’s the secret Thoreau has to offer, that promise that the world is sweet. That’s the rain which must feed this new river. “I learned this, at least, by my experiment; that if one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.” We must trust that he is right—for ourselves and, though he couldn’t have guessed it, for the planet.