There’s a scene late in Brokeback Mountain, Ang Lee’s much-awaited big screen version of the award winning gay love story by Annie Proulx, where a shut-down, frightened Ennis del Mar—devastating Heath Ledger, as one half of a poignantly stifled, decades-long love affair—finally breaks, collapsing into the arms of his exasperated soul mate, Jack Twist, played with open-hearted vitality by Jake Gyllenhaal. Ledger’s Ennis, whose muted, marble-mouthed, speak-only-when- necessary implosion cracks with tears of a life wasted, sobbing into Gyllenhaal’s embrace. As movie moments go, it’s just incomparable.

Ang Lee’s sad masterpiece begins in Sygnal, Wyoming, circa 1963, as two young men—hushed ranch hand Ennis del Mar (Ledger) and the more rowdy rodeo rider Jack Twist—score a summer job herding sheep up on isolated Brokeback Mountain. They’re both lonely souls with albeit different demeanors, alienated from family and inching toward a tentative friendship. The majestic setting, expertly shot in lyrical, poetic mastery on the Canadian Rockies by the world-class cinematographer Rodrigo Prieto, conspires to enchant the two as their friendship bonds deepen through their shared meals and campfire confidences.

And here Brokeback Mountain becomes a landmark film, as the two unlikely cowboys fall consumingly into passion and sex, which gives way to something more difficult and unexpected—love. "I ain’t queer" Ennis tells Jack (and himself) and though it’s a "one shot" deal as Ennis says, they find a freedom and intimacy in the wide open space that liberates them both—until the summer ends.

Four years pass and both marry women. Ennis and sweetheart Alma (a powerful Michelle Williams) have two daughters, while Jack settles with wealthy Lureen (Anne Hathaway) in far off Texas. Until one day when Jack looks up Ennis, and they reunite in a scene of released, pent-up longing that’s about as romantic as anything we’ve seen in American movies, period. It doesn’t take Alma long to read them—yet they embark on a clandestine love affair, meeting in secret a few times each year, going on "fishing" trips together, giving in to tenderness year after year, until their opposing ideologies begin to eradicate their lives and their own livelihoods.

And here, Brokeback Mountain becomes a master class in how a film can distill—then uncork—passion and pain. Ennis’ marriage dissolves, while Jack and Lureen drift. Despite Jack’s yearly pleas to live together in love, Ennis, scarred by a childhood memory of an openly gay cowboy couple bashed to hell, can never reconcile his head and heart. Instead, he becomes a shell of a man—penniless, drifting from odd job to odd job, nearing forty with nothing to show for it, and emotionally cut off from the world. Even a sympathetic waitress (winningly played by Linda Cardellini) can’t scale his walls. To watch Ledger and Gyllenhaal play these scenes is to see the process of falling deliriously into love, then later losing hold of each other, victims of time, society and consequence.

And then comes the big scene at the end of the film involving a very simple shirt, a revelation across an actor’s face and into the audience. It’s one of the most memorable of all contemporary movies, and played delicately by Ledger, it’s a jolt of emotion that pours out of him and us.

Ledger’s searing performance is one for the ages, and though superlatives are thrown around routinely come awards season, this is quite simply, an unexpected, classic piece of acting on par with the all-time greats. A major star hasn’t surprised us like this since, well, Charlize Theron in Monster not so long ago. In a towering turn that’s equal parts fear, secret liberation and sadness. And Jake Gyllenhall, the more mercurial of the two, is galvanic in his direct, clear-eyed need for Ennis and an identity for their love.

Brokeback Mountain is a lot of things—an epic and rapturous poem to love lost, and a heartrendingly melancholy take on the consequences of a life never lived. Mostly it’s the study of an unforgettable, simple man ensnared in a merciless, complex life. The movie travels the deep themes—love, disillusionment and loss—where American films never go. It’s a revolutionary film, with the power to change hearts and minds.