“You will start to feel a reaction in about half an hour,” the shaman, Tsumpa, said, as my guide translated. “When the effects come, you must concentrate on what the medicine is trying to communicate.”

The open air of the hut, animated with night sounds, grew still with expectation. Tsumpa grimaced as he drank the brew. After pouring a bowl for me, he cupped the gourd in his hands and for several minutes whistled a sweet melody into it — the high key of a tin whistle or courting bird, seducing the plant spirits to aid me.

The potion tasted acrid and bitter. I rinsed my mouth with water before rolling tobacco into a plantain leaf cigarette.

And then I waited.

It was the final night of my weeklong trip to explore the Ecuadorean rain forest and an indigenous people, the Achuar, who, for more than a decade, have been using limited tourism as a means to preserve and protect their land and way of life. I had traveled by car, plane, boat and foot — more than 100 miles from conventional civilization — to reach a place where the old ways have not been forgotten, where local people interpret the world through their dreams and the forest spirit known as arutam is said to inhabit the mighty kapok tree, and where healing and insight is sought from a hallucinogenic plant brew the Achuar call natem, known elsewhere as ayahuasca, or “vine of the soul.”

The trip was to be a departure from the typical Amazon tourism, which tends to package wildlife viewing with a certain cultural voyeurism. I wanted something more immersive and participatory: an experience with Ecuador’s indigenous people that would expose me to a different orientation altogether. Casting myself into a world that was utterly foreign, I hoped to return with new insight into the familiar.

Earlier in the week — an evening in late spring — I had landed in Quito, Ecuador’s capital, which sprawls at 9,350 feet along the base of an active volcano in a distinctive atmosphere of thin air and diesel fumes that aroused dormant memories of the semester I had spent there during college. With me was David Tucker of the Pachamama Alliance, a San Francisco-based nongovernmental organization that supports the cultural and territorial rights of Ecuador’s indigenous people and operates specialized tours into their homeland.

David had arranged for us to drive early the next morning to the Amazon basin, fly to a remote community that had recently built a small tourist camp in the forest, and then travel by foot and river to a more established lodge. Only despite a long layover, our bags were delayed from Miami — an inauspicious start that would waylay us a day. David thought I might want to experience a “cleansing” from an indigenous Quichua shaman he knew living in the highlands two hours north of Quito, and the next morning hired a car to take us there.

The shaman’s two-floor yellow cement home was modest but the stateliest around. A square altar to Jesus, crammed with crosses and tiny portraits, stood in the waiting room. The shaman, named Don Esteban, emerged wearing a knit V-neck sweater and slacks, beaded necklaces and a yellow-feathered headdress. He beckoned us into the adjacent treatment room, which was sparse and dim and smelled of burnt sugar cane alcohol. I was directed to sit in the corner beside a desk cluttered with melted wax, glass balls, brown eggs and various other mystical paraphernalia.

Don Esteban sat opposite me, next to his wife, a smiling woman with an array of gold teeth. “Here, rub this over your body,” he said, handing me an unlighted candle.

After I did so, he sparked the flame and gazed into it intently. “Andres espiritu, Andres espiritu,” the shaman incanted. “Your spirit is not tranquil. It is sad, and longs for a new energy and path. It is struggling to balance your health, work and body.”

I told him that my father had died two months earlier. “That is why there is sadness and disequilibrium,” he said. “This ceremony, and spending time in the mountains with Pachamama” — Mother Earth — “will help make your spirit whole.”

Don Esteban had me stand naked in the center of the room. Beating a drum and chanting around me, he summoned the ancestral spirits before instructing me to face the four directions of nearby volcanoes in turn, with arms raised, as he blew tobacco smoke on my skin and slapped me with nettle leaves. Then, with his cheeks engorged with alcohol, he held a candle flame to his lips and unleashed spectacular balls of fire that dissipated across my chest.

I looked on these ministrations with skepticism but was left feeling serene, and believing that my visit there had been serendipitous. Whether by intuition or sheer speculation Don Esteban had recognized my grief, and made it a central theme for the journey forward.

Riding back to Quito, I reflected on what the shaman had gone on to say. Three times, he had placed rose petals sprinkled with floral water into my palms, and told me to rub them all over from head to toe.

“Andres,” he said all the while, “open your heart.” When we arrived at the hotel that night, our bags from Miami were awaiting.

The five-hour drive east from Quito into the Amazon basin passes through a highland corridor known as the Avenue of the Volcanoes. Pichincha, Cotopaxi, Antisana, Illiniza — their snow-white peaks rise above Ecuador’s fertile central valley like giants, and Andean indigenous people humanize them as such, relating to them as elder family members who hold great influence. This can sometimes be very handy: I was told of a pregnant young girl who dealt with her father’s disapproval by blaming the cause on the Imbabura volcano. Who was he to argue?

Our flight into the jungle was to leave from Shell, a one-street frontier town on the edge of the Amazon basin that was established by the Shell oil company in the 1930s as a base for prospecting. After 20 years, Shell left and evangelical Christians moved in — embarking on their own kind of prospecting from the town’s small airport. (They’re still there.) But when we arrived, flights were grounded because of rain. We were told to return the next day; David suggested we drive to nearby Puyo, the provincial capital, and meet some Achuar leaders.

Numbering around 6,000 on an ancestral territory of nearly two million acres in southeastern Ecuador, the Achuar people were among the last of the country’s rain forest tribes to be contacted by outsiders, when some Salesian Catholic missionaries arrived in the 1960s. Elders say that in the early ‘90s they began having dreams about an imminent threat coming from the external world. Soon after, they learned that the western edge of their homeland had been given over to Arco as an oil concession.

Most of Ecuador’s estimated 4.7 billion barrels in crude oil reserves — the third largest in South America — lie under the northeast Amazon region, where foreign corporations have left a legacy of pollution and displacement that has been widely decried.

But the Achuar had watched watching northern tribes struggle against oil companies, and beginning in 1991 were able to organize their scattered — and historically warring — communities into a political entity that has so far saved them from a similar fate.

Recognizing a need for outside allies, they met with a group of Americans to form the Pachamama Alliance, which for the last 15 years has helped the Achuar and other Amazonian indigenous groups from its Quito office with land titling, skills training, economic development and policy advocacy.

With proponents of oil development — including Ecuador’s president — continuing to press for exploration on their land, the Achuar now find themselves embroiled in a classic struggle for power and resources that native people have almost always lost.

We found Chumpi Tsamarin (also known as Luis Vargas) who had been the Achuar’s first president, seated inside the restaurant he opened on a side street in Puyo. Mr. Tsamarin, who has also led the political organization representing all nine of Ecuador’s Amazonian indigenous groups, described the current territorial struggle in terms of psychological warfare (he saw “Avatar” as an affirmation of their cause, but thought the violent tactics depicted in the film were not inevitable); the Achuar, he said, feel staunchly resolute about their right to defend what is theirs. As they see it, our collective survival is imperiled by the modern “dream,” as he put it, that sees nature as an endless fount of resources.

So far, Mr. Tsamarin said, tourism has presented the most viable, nonpolluting source of economic security. In 1996, the Achuar opened Kapawi Lodge & Reserve, which receives an average of 1,000 visitors a year. Last month the United Nations named it one of the top five outstanding environmental conservation and community development projects in the world. Though the lodge was initially set up in joint partnership with an Ecuadorean tour company, the Achuar have assumed full ownership. Most of its 30 staff members are natives, and some received hotel management training in Quito.

But the benefits of tourism have a corollary, and Mr. Tsamarin lamented them: the loss of communal values and a new market mentality, alcohol abuse, litter, men cutting off their traditional ponytails. The Achuar now want to expand a controlled form of tourism farther into their territory, and have built a camp in the forest near the remote community of Tiinkias to offer visitors a more rustic experience than Kapawi. I would be the first tourist there.

After spending a night at the luxuriant El Jardín Hotel in Puyo, we were cleared for takeoff the next afternoon in a small Cessna operated by Aerotsentsak, the Achuar’s aviation service. From on high the metaphor of the Amazon as earth’s lung came to life: below us, wispy clouds lingered over the virgin forest as vaporous exhalations while mocha-colored rivers coursed through it like capillaries.

After an hour, we landed at a dirt airstrip beside Chichirat, a forested settlement of 10 families north of Tiinkias.

I immediately felt transported by the absence of mechanical ambience, as though the soothing sounds of nature were reaching me through noise-canceling headphones. David and I stepped off the plane as dozens of villagers stared at us quizzically, and a man with a round face and thin mustache walked forward, introducing himself warmly as Shakai. He would be our guide. As children carried off our bags, Shakai led us into the elliptical communal house built over the dirt with a high palm-thatched roof and open walls, and divided along gender lines. Males sat on benches around the perimeter; women clustered in the back.

In short order, I was handed a red clay bowl painted with black-and-white shapes, filled with the staple brew of sweet fermented manioc called nijiamanch. A performance began: a woman walked up to me and sang shyly in Achuar about a sunny day alone in the forest, when she missed her husband, but was comforted knowing that he was somewhere witnessing the same sun. In a fragile falsetto, a young man with a long ponytail voiced words meant to ward off a bad omen he received. I was handed a drum and told to meander around beating it, to the amusement of all, while a girl hopped erratically beside me in a kind of courtship dance.

Their unpolished performance was touching, and being the first ever for a tourist gave it the feeling of historical significance. But this also troubled me, as I considered how my arrival marked the ushering of changes that Mr. Tsamarin had described. And yet there’s this unexpected upside. Such quaint cultural displays meant to satisfy tourists expecting something “authentic” and exotic can also resuscitate and revive aspects of traditional culture. “It makes us see how we’re admired and validates the importance of our traditions,” Mr. Tsamarin had told me, adding that the Achuar now consider the value of their cultural heritage as a useful leverage against oil development.

It became too late to travel on to Tiinkias, so we ate dinner — a crispy heliconia leaf stuffed with steaming wild turkey, palm hearts and green onion — in the thatched house of the local shaman, and pitched tents on the wooden floor of the schoolhouse.

That night I dreamed of my mother and father defending the rain forest, and later, of Ben Stiller announcing a televised ski race in an Afro wig. When I awoke at 4 a.m., roosters were already declaring it daytime through the pitch darkness. The Achuar typically rise at this transitional hour to drink guayusa, a caffeinated tea grown in the forest. It is a time when fathers pass on values to their children, mothers teach skills to their daughters and dreams are interpreted.

The local shaman, Jippeikit, told me that my first dream was about my father wanting to reunite with my mother — “Even when we die, our souls still exist,” he said. The skiing dream, he sensed, was a story of competition, which boded well. “When you visit another area,” he said, “you will not have any problems.”

We reached Tiinkias after a short trek through the muggy forest and a motorized canoe ride downriver. Its two dozen inhabitants were awaiting us in the communal house, beside a dirt clearing with a volleyball net woven from plant fibers. Laundry hung to dry between thatched-roof dwellings. An uneven footbridge spanned part of a small lagoon where a caiman rested on a log.

Over two idyllic days I found myself content simply in the Achuar’s mellow presence. We spent hours in the communal house drinking nijiamanch, tended by women constantly squeezing the pulp by hand. Often, some story I couldn’t understand provoked fits of laughter. I sang a bluegrass gospel number for the Achuar; David played guitar. Each morning, I had my dreams read by an elder.

We slept in the new tourist camp, built on a forested knoll just outside the settlement, with a simple layout of elevated wooden platforms covered by thatched roofs that extend into eating and sleeping areas meant to accommodate the groups of up to 16 visitors they anticipate.

Shakai became not just my guide to the forest but also its interpreter. In a nondescript leafy plant he saw a remedy for gastritis; in an electric blue morpho butterfly that fluttered erratically past, he saw the ears of a deceased ancestor. “What does a stick bug represent?” I wondered aloud. Shakai said it was just a stick bug.

One afternoon we passed a kapok tree, 150 feet tall with splayed buttresses and thick, weeping vines, which Shakai explained as a home of arutam: the spirit of the forest, and ancestors.

When Shakai was 13, he said, like all Achuar boys, he ventured into the forest alone to find arutam. For three days prior he fasted. He then laid a seat of palm leaves beneath a kapok tree and prepared the sacred forest medicines: datura and natem, hallucinogens that produce potent visions.

Arutam first arrived, the Achuar believe, in a form of strength: a jaguar, or sometimes an anaconda, or lightning. If one becomes afraid, it is said, arutam disappears. But move toward it courageously, and the vision is supposed to transform into an elder ancestor, who reveals one’s life calling.

During this rite of passage, Shakai saw himself working with outsiders he’d never seen before. When Kapawi Lodge was built many years later, Shakai would become one of its first guides.

We reached Kapawi by motoring down the Bobonaza River, up the wide Pastaza, to the Capahuari — a four-hour journey that dipped us briefly into Peruvian territory. The lodge is set on a sheltered lagoon; 18 palm-thatched bungalows, built on stilts above the shallow water in traditional Achuar style — without nails, but with modern comforts like solar-heated showers and eco-friendly flush toilets — are connected with airy dining and lounging areas by an elevated boardwalk. The lagoon behaves as a town plaza for bird life, and screened back walls and shaded balconies ensure that guests are always well positioned, from bed or hammock, to observe its lively happenings.

It was the low season, and we and a German couple were Kapawi’s only guests. Visitors typically fly in from Shell on four-, five- or eight-day packages of standard jungle lodge fare: dugout canoe rides, guided forest walks, and spotting animals (Kapawi’s remote location within a protected reserve offers a particularly excellent chance of that). Riding back the next morning from a clay lick enjoyed by chestnut-fronted macaws, we came across pink river dolphins. Later we paddled a canoe looking for anaconda but returned satisfied by yellow-rumped caciques nesting beside hoatzins, a prehistoric-looking, pheasant-sized bird with a spiky mohawk. Alone on Kapawi’s self-guided trail one afternoon, I startled (I should say the reaction was mutual) 30 ring-tailed coatis, which leaped onto tree limbs and then fixed me with beady stares.

But Kapawi places an emphasis on cultural activities, and guests can learn how women make nijiamanch or spend a night in a local Achuar community. Lodge staff members can also arrange participation in a dream-sharing ceremony with guayusa tea. But through a local shaman who knew and trusted David and Shakai, I received a special invitation to drink natem, which is how I landed, on that final evening, in Tsumpa’s house.

Tsumpa and his wife, along with a dozen children and grandchildren, live by themselves high above the Pastaza River on a tidy clearing ringed by coconut palms, manioc plants, fruit trees and a garden of various plant medicines. It was dusk when we arrived; in the distance, isolated cumulonimbus thunderclouds were set aflame by the pink-orange sun. Tsumpa was seated within a bucolic tableau: his sturdy wife prepared bowls of nijiamanch and tended to chores, while one daughter sat on a bamboo platform breast-feeding and another wove a headband. Dogs napped on cold ashes; an orphaned, saddle-backed tamarind monkey hopped onto a bunch of plantains; a toucan perched on a nearby log.

Tsumpa served me the natem in an adjacent hut. All appeared normal, until after what seemed like 20 minutes it no longer did. A montage of images emerged from the darkness — neon crystals, a lion. Soon my body dissolved into the surroundings, swallowed by a sea of energy. Unmoored and disoriented, I was adrift in a more expansive reality.

This brought a greater awareness, and I began to perceive things that had been imperceptible, like a low-frequency vibration permeating the environment. The hum of the universe? My thoughts drifted between visions. I imagined myself basking in the sun on the flanks of the volcano Chimborazo. I saw images from childhood and of random friends back home, all presented like scenes from the narrative of my life. Then my father appeared, seated in a chair before me, like a ghost. For several minutes we exchanged the sentiments that I had regretted not expressing before he died: What a life we shared, we both seemed to say. I looked down and noticed I was sobbing, and when I looked back up, he was gone.

Tsumpa was whistling and shaking leaves around a sick baby that had been brought to him for a cleansing, and Shakai asked if I’d like the same. I sat before Tsumpa and felt his hands on the crown of my head. His whistling seemed to conjure a protective field; in the leaves fanning my shoulders, I sensed a dusting of energy.

“Look at the stars,” Shakai said. The night was alive and glorious. Stepping outside felt like entering a larger room, the constellations stretching overhead as a low-hanging ceiling. David noticed my lingering sniffles and offered a bowl of tobacco-infused water, a traditional remedy, to clear my nose. Snorting it triggered a surge of intense sensation and then violent waves of vomiting unlike any I had ever experienced. More bizarre were the accompanying sounds: primeval bellows so loud and resonant they seemed to echo for miles. After, I could hear Tsumpa’s daughters giggling, and soon we were all laughing.

I laid myself down on a palm leaf, spent and contented. David and I chatted into the night. The Achuar conversed in their huts. Babies cried and were hushed. A gunshot went off in the forest, the sound of a lone man hunting. Within this dynamic nightscape, the boundaries between waking and sleeping, between inside and outside — indeed between humans and nature — blurred to nothing.

I awoke refreshed after a few hours of sleep, no longer feeling the queasiness that had been bothering me for two days. Sipping a coconut from Tsumpa’s tree, I asked the shaman what he had noticed in me.

“Andres,” he said simply, “You came here to learn about the culture, the rain forest and reality of the Achuar people. Now you’ve seen that.”

David and I returned to Quito later that morning and parted ways. I had given myself a few more days in Ecuador without a plan, but now I knew where to go. I traveled south through the highlands to Riobamba, and then ascended to Estrellas de Chimborazo, a cozy mountain lodge set beneath Ecuador’s highest peak, “Father” Chimborazo — some say that elevated by the equatorial bulge, it reaches closer to the stars than any spot on Earth.

I took walks alone through the surrounding páramo, the bushy, blond grassland carpeting the volcano’s flanks, past grazing alpacas, and lay for hours on my back.

It was precisely the time with Pachamama that Don Esteban had prescribed for me. And as I had envisioned myself.