"How happy is the blameless vestal's lot!" writes Alexander Pope, whose poem "Eloisa and Abelard" lent this wonderful fantasia its title: "The world forgetting, by the world forgot. Eternal sunshine of the spotless mind!"

Joel Barish (Jim Carrey) is one of Pope's blameless vestals. After his girlfriend Clementine (Kate Winslet) leaves him, Joel cannot determine how their relationship failed or why she now acts as if they've never met.

The latter is easily answerable: Barish discovers that she underwent brain surgery at Lacuna, Inc., a psychiatric firm founded by Howard Mierzwiak (Tom Wilkinson) that specializes in "the erasure of troubling memories."

Acting out of personal retribution Joel receives the treatment himself, hoping to cleanse Clementine from his thoughts.

After Mierzwiak's staff commences the late night operation, however, Joel realizes the value of those memories. Hoping to preserve Clementine in his past, he embarks on a whirlwind goose chase through his mindscape, leaping through their cherished moments while attempting to smuggle his ex into

memories where the Lacuna team cannot find her.

Despite his efforts, Joel's mental world pummels forward in the forgetting "procedure," and the cerebral dynamic makes for a literally dizzying head-trip.

Beautifully constructed, immensely moving and resplendent with bursts of emotions, colors and moods, "Eternal Sunshine of the Spotless Mind" is a Valentine's Day card for the spurned lover in all of us. Onscreen romantic

bliss hasn't been this weirdly fetching since Barry Egan and Lena's lip-locked silhouette in "Punch-Drunk Love's" ebullient Hawaii sequence.

Cinematic romanticism also hasn't been as unconventionally plotted or transcendent. While Paul Thomas Anderson and Adam Sandler's 2002 collaboration artfully glided over the emotional specificities in Egan's

relationship, "Eternal Sunshine" gazes at a relationship in its entirety, lingering over the passing details, the backward glances and the guarded conversations between two lovers.

This fantastical pastiche of memories results in one of the grandest, most poignant love stories in quite some time.

The fact that director Michel Gondry (the Frenchman responsible for the White Stripes' recent string of video triumphs) and Charlie Kaufman (who penned the outré "Being John Malkovich") cooked up the scenario is

additionally remarkable. Known for their conceptual brilliance and originality, the resonance they achieve here is unprecedented.

The reclusive Kaufman always interspaces his plots with personal, graceful feeling. With Joel and Clementine's relationship, however, the curly-haired wit fashions his most fully realized story. Equipped with a fractured

chronology and Kaufman's sleeve-worn cleverness, every character feels more well-rounded and realer than ever before. He's also found another felicitous director in Gondry, who can stand alongside Spike Jonze as a Kaufman collaborator.

Gondry previously adapted Kaufman's "Human Nature," an underrated debut that hints at the visual bravado he brings to their latest joint effort. The director mounted "Eternal Sunshine" with the imaginative enthusiasm and

confidence of an old pro. He stages terribly complex sequences — set in a man's proverbial mindscape no less — at perfect, off-kilter tones, allowing his two leads room to make mind-hopping look like the most natural thing in

the world.

Equally astonishing is the lead performance of Carrey, who attains the perfect mesh of humor and pathos he's been pursuing for years. Joel is the most atypical character Carrey's ever played: Reserved, pensive, unsure of

himself, he's the polar opposite of Ace Ventura and unquestionably gives rise to the actor's finest performance.

Initially, Winslet's rebellious Clementine is off-putting, maybe even grating at times. But the actress inflects her character with vulnerability and compassion, and by the zigzagging third act, Clementine's zeal could melt an iceberg.

The adroitly cast Lacuna employees are very amusing. Elijah Wood and Kirsten Dunst take a respite from their franchise appearances and give loose, relaxed performances; cast against type as a nebbish technician, Mark

Ruffalo is his typically flawless self; and Wilkinson manages to bring gravitas and integrity to his small role as Lacuna's founder.

In spite of its outlandish qualities and chaotic rhythms, Kaufman and Gondry's film is hardly as esoteric or impenetrable as the story suggests.

Like a first meeting between soul mates or a fading image of one's first kiss, it harnesses onto your mind and stays there, offering a treasure trove of passion, hesitation, pain, regret and love. It's an outright masterpiece.

Grade: A

Focus Features presents a film written by Charlie Kaufman and directed by Michel Gondry. Starring Jim Carrey

(Joel), Kate Winslet (Clementine) and Kirsten Dunst (Mary). 108 minutes.