For the technicians who run Lacuna Inc. (check out their Web site, www.lacunainc.com), Valentine's Day is their busy season. Lacuna founder Dr. Howard Mierzwiak (Tom Wilkinson) has discovered a simple and effective method to erase toxic, problem memories. So if you've been summarily dumped by a mate or lover, you need not live with the tortured recollections of the past. There is hope.

Is there any risk of brain damage? Well, technically speaking, the procedure is brain damage, says Mierzwiak, but that doesn't stop Joel (Jim Carrey) from submitting himself to an all-night session with Lacuna's crack team of technicians after he discovers that his girlfriend, Clementine (Kate Winslet), has had her memories of their up-and-down relationship erased.

That the premise of "Eternal Sunshine of the Spotless Mind" seems somewhat grounded in reality - not to mention humanity - makes it something of a departure for screenwriter Charlie Kaufman, the meta-master behind such films as "Being John Malkovich" and "Adaptation." Not everyone will agree, but I'd say "Sunshine" is Kaufman's best work to date, an amazingly complex and yet strikingly affecting look at love, life and memory that gives us one of the great movie love stories ever told.

The film is the second collaboration between Kaufman and director Michael Gondry. It's a huge leap forward from their first movie, "Human Nature," largely because the material plays into Gondry's strengths as the kind of gifted visual filmmaker who can turn kaleidoscopic images to his advantage. And boy, does he have a lot to work with here.That's because shortly after the erasing procedure begins, Joel decides that even the worst memories of his time with Clementine are worth cherishing. But he can't simply flip a switch - he's asleep, after all. And even though the technicians running things (the brilliant supporting cast of Mark Ruffalo, Kirsten Dunst and Elijah Wood) aren't exactly the most attentive bunch, the process, once it begins, is ruthless in its systematic destruction."Sunshine" careens back and forth between memory, fantasy and reality with Joel reliving his relationship with Clementine in the topsy-turvy, collapsing labyrinth of his own mind. Several scenes find him trying to escape Dr. Mierzwiak and his minions by burrowing into deeply repressed memories, allowing Carrey to play Joel from infancy to adolescence. (Watching him splash in the kitchen sink, reveling in a warm bath, is one of the most joyful sights the movies have given us recently.)As remarkable as Carrey is in these bravura sequences, it is his splendid low-key work as the yearning sad sack that is most impressive here. And Winslet again demonstrates her amazing vitality as an actress, giving the fiery Clementine, a self-described "nutso," a damaged undercurrent that makes you understand why Joel loves her."Sunshine" (like all of Kaufman's films) poses a lot of questions about the meaning of life and the role of fate. (It also evokes the devastating tragedy of Alzheimer's disease.) But, at its heart, it is an amazing love story, not because its participants are all that extraordinary, but because it has the courage to show the affairs of the heart, warts and all, in all their fragile glory and mundane banality. The message: Love isn't just necessary. Love is us.Is it worth the anxiety, the anger, the inevitable ruts, the potential for ruin?Do you really need to ask?