“But isn’t Sean Penn a self-important jerk?” asked my cousin when I told him how much I liked Into the Wild, which Penn scripted and directed. I replied that Penn does indeed have that reputation, which I tend to believe, yet history hardly suggests that estimable works of art always come from simpatico human beings. The opposite might be closer to the truth, in fact.

Still, my cousin’s skepticism was the same that I took into the movie theater, and his surprise in hearing my report mirrored mine in giving it. Quite simply, Into the Wild is the most unexpectedly astonishing experience I’ve had in a movie this year. I was transfixed while watching it, high on its spell when I came out, and I’ve barely stopped thinking about it in the days since. I will be additionally surprised if I don’t end up regarding it as 2007’s best film.

It is, far and away, the best movie Penn has made, yet also a vindication of those earlier works’ ambition. And if it comes from a putative self-important jerk, that fact may end up being oddly germane to its achievements, since it describes a number of fascinating and troubling human paradoxes through the story of one unforgettable yet deeply perplexing young American.

His name was Chris McCandless (Emile Hirsch), and his fame owes to the fact that, four months after walking into the Alaskan wilderness one day in the spring of 1992, when he was 24, he was discovered dead of starvation, having failed to bag enough game to feed himself and, perhaps, having inadvertently weakened his health by mistakenly eating poisonous plants. He was not a suicide, though some might put “intentional” in front of that noun.

McCandless’ story was told by writer Jon Krakauer first in a 1993 Outside magazine story, then in the 1996 bestseller Into the Wild. Penn acquired the rights to the book early on, but getting the movie made took a decade due to numerous obstacles including his arduous, eventually successful, campaign to enlist the cooperation of McCandless’ family.

“Intense” and “idealistic” are words people used to describe McCandless. Raised in a Washington, D.C., suburb, he was a star athlete and top student in high school, yet talked of going to South Africa to fight apartheid. A devotee of Leo Tolstoy, he admired the Russian count’s decision to leave a life of privilege to live among the poor. When McCandless graduated from Emory University, his parents thought he was headed for Harvard Law.

Instead, he gave the $24,000 in his college fund to charity, then hit the road. For the next two years, until his death, he roved all over the West, working on a farm in South Dakota, flipping burgers, riding the rails, canoeing down the Colorado River to Mexico, sleeping under the stars or in homeless sheltersand never once contacting his colossally worried family back East.

In Sean Penn’s previous movies, the aspect I’ve admired most has been the writing, and here he does a phenomenal job translating Krakauer’s terrific book into an intricate, sinuously unfolding picaresque drama. Starting with Chris’ arrival in Alaska, and repeatedly returning to his months of adventure and adversity in the wilderness, the story flashes back to his graduation from Emory, then traces his subsequent peregrinations, while occasionally revisiting his childhood conflicts with his parents, Walt and Billie (William Hurt and Marcia Gay Harden), and fond relationship with his younger sister, Carine (Jena Malone).

Penn’s direction is equally supple, resourceful and variegated. Rather than hewing to any tight formal concept, he keeps things admirably loose and observant, alternately suggesting models ranging from Robert Altman’s puckish spontaneity to Terrence Malick’s rapturous lyricism. When humans are the center of attention, the camera is often up-close and skitterish. When nature takes over, we are given stunningly articulated views of some magnificent landscapes. And while this close-up/long-shot interplay summons up a fundamental tension at the heart of the film’s drama, every scene brims with an energy and an inventiveness that show Penn constantly challenging himself.

It’s no wonder that he would, given this material. How often do you come across a straight-out-of-the-newspaper story that so seamlessly blends the anecdotal-everyday with the mythic, the epic, the archetypal? That may sound far-fetched, but see for yourself: In McCandless’ story are resonances that range from The Odyssey, grail quest narratives and Pilgrim’s Progress to the bildungsroman tradition, the European Romantics, Walt Whitman and other American authors who McCandless consciously emulated, including H.D. Thoreau and Jack London. Indeed, its theme of attempted self-reinvention through westward voyaging is the American story, from Columbus to Kerouac. As for cinematic resonances, well, start with the obviousEasy Rider.

Like Dennis Hopper’s iconic hippie-biker epic, Into the Wild serves as a firsthand tour of a big chunk of America. Watch the end credits and note that Penn apparently shot in every little burg and far-flung landscape on Chris’ long and winding itinerary, giving his mythic narrative a sensory grounding that’s as much concrete geographic poetry as documentary reportage.

Into the Wild also resembles Easy Rider in showing its protagonist moving through a succession of diverse human situations yet ultimately leaving them all behind. In Hopper’s film these situations were varied visions of community; in Penn’s they are, quite obviously, surrogate families. Those to whom Chris temporarily attaches himself include a farmer (Vince Vaughn) who takes him on as a worker, an itinerant hippie couple (Brian Dierker and Catherine Keener) with a missing son of their own, and, most movingly of all, a lonely retiree (Hal Holbrook) who offers to adopt Chris as his grandson.

All of these people would like to give Chris a chance to forge new human connections. Is he right to reject them, when the alternative is the road to Alaska, solitude and death?

Here we hit the nub of Penn’s film. As much as I love Into the Wild, I’ve met people who absolutely hate it, and I understand why. It all comes down to Chris.

When Outside published Krakauer’s original piece about McCandless, it generated more mail than any article the magazine had ever printed, and the responses suggested that Chris’ story serves as a Rorschach test for everyone who encounters it. “Some readers,” Krakauer wrote, “admired the boy immensely for his courage and noble ideals; others fulminated that he was a reckless idiot, a wacko, a narcissist who perished out of arrogance and stupidityand was undeserving of the considerable media attention he received.”

Surely the most admirable thing about Penn’s film is that it doesn’t attempt to resolve this challenging dichotomy. In Hirsch’s winning, ambitious performance, Chriswho rechristens himself Alexander Supertrampis prickly, headstrong and uncompromising, but also fun-loving, high-spirited, generous and friendly. No dour ascetic, he pursues an odyssey dedicated to joy and ecstatic discovery. In that, he’s like many a 20-somethingonly more soand will remind many older viewers of their younger selves.

At the same time, Chris takes things to an extreme few people would consider defensible. His treatment of his family, in particular, seems unaccountably selfish and cruel. If he really believed in the ideals of kindness and generosity, why would he torture those closest to him by remaining incommunicado? Even when he obviously knew he was near death, he left no note to his parents and sister saying, “Please forgive the pain I’ve caused you.” Krakauer’s book makes clears that the McCandlesses have suffered every day since Chris’ demise, and they always will.

No doubt, Chris carried a serious load of anger after discovering that his father had been a bigamistand thus, in his eyes, a liar and hypocriteafter Chris was born. Surprisingly, Penn not only relays this information, but also, unlike Krakauer, portrays Walt McCandless as a violently abusive husband. Is this true? I have no idea, but Penn has suggested that the McCandless family went along with their very unflattering portrayal here as an act of “penance.”

Yet to understand this story simply as an example of family or individual dysfunction would be, I think, to miss its true significance. For Chris’ voyage to Alaska clearly was no act of escape or revenge. Rather than a flight from reality, it was a daring leap toward Reality. Like the “vision quests” enacted by young Native Americans, this plunge into wilderness and isolation was a self-imposed ritual of initiation, an effort at “rebirthing” that only had a chance of succeeding if it involved risking everything.

In traditional societies, such rituals occur under the guidance of tribal elders and enjoy the support of the entire community. In our world, there are no such supports, so the individual effort can turn out, or appear, suicidal.

But does Chris’ death brand his initiation as unsuccessful? How could we presume to say? Chris might have lived and come down that mountain no longer a restless, troubled boy but a whole, centered and forgiving man. That he stayed on the mountain, forever, tells us only that the battles he fought occurred in the realm of the spirit, where indeed he may have emerged cleansed, free and victorious.

Into the Wild opens Friday throughout the Triangle.