Every week this summer, we'll be taking an historical tour of the Hollywood blockbuster by examining an older film that is in some way a spiritual precursor to one of the weekend's wide releases. This week: Pixar's grand return to artistic greatness, Inside Out, goes inside the human brain to take one look at how our minds interact with our memories. Here is another such look.

Eternal Sunshine of the Spotless Mind has been one of the most highly-regarded films of the 2000s virtually since the moment it first appeared on the scene in March, 2004, and I'm damned if I can come up with a reason to challenge that perception. It is, honestly, an example of exactly the kind of film that everybody wants every film to be. For it is genuinely conceptually audacious, one of the vanishingly minute number of movies made in the past 15 years to be actually, legitimately Like Nothing You've Ever Seen Before. And at the same time, it's so flawlessly executed that it feels less like a brand new idea being worked out for the first time, than a refinement of concepts and techniques that have been kicking around forever, waiting for their definitive treatment.

With any movie that is so generally flawless, it's hard to know quite where to start with it, so let's just start with the two incompatible personalities that met to produce the idea of the film. The story was by Charlie Kaufman, Michel Gondry, & Pierre Bismuth, the last of whom has no other contributions to film worth talking about, so for ease we'll think of this as primarily the collision of Kaufman and Gondry. The former was already the screenwriter of Being John Malkovich and Adaptation., two immaculately over-conceptual metamovies that spoke to an immense well of pensiveness and the terror of being alone; four years after Eternal Sunshine, Kaufman would write and direct Synecdoche, New York, which pretty much confirmed that his major fascination as an artist was the combination of perceptual mindfucking in service to a bleak, almost depressive concept of how the world works. Gondry, meanwhile, had only made one film - the Kaufman-scripted misfire Human Nature - but he had an extensive catalogue of music videos to his name that showed him to be a great visual fantasist with an impressive sense of using camera trickery as a form of playing with the medium, childishly having fun with visual representation almost aggressively disconnected from any sense of emotional rigor.

The combination of abject depression and flighty joyfulness should be baffling as all hell, but Eternal Sunshine profits immeasurably from having those two irreconcilable impulses driving it. Kaufman's morbidity concerning the basic hopeless of romantic relationships provides the emotional spine of one of the most insightfully sad explorations of the human drive for love since Annie Hall concluded that we need the eggs. Gondry's love of showy practical effects and dazzling post-production meant that this exploration could be achieved inside a movie whose insane structure, both narratively and visually, allows it to replicate the fluid, discontinuous process of thinking and remembering like literally no other coherent narrative film I can name

Such a complex topic gets the unabashedly complex treatment it deserves, beginning with a narrative structure that's almost impossible to parse until it's almost over; I clearly remember seeing it for the second time and having one of the biggest "ooooh, that's what that means" moments of my moviegoing life when I realised what the hell the first 17 minutes were all about. They are, for the record, the short story of how Joel Barish (Jim Carrey) decided one day, quite out of nowhere, that he needed to go to Montauk on this wintery day. On the train, he meets a woman with a bright orange coat and bright blue hair, Clementine Kruczynski (Kate Winslet), and they're both positive they've seen each other before. The best they can come up with is that Joel has probably shopped in the bookstore where Clementine works, which clearly isn't a satisfying answer. They enjoy each other's company so much that the return together to Clementine's apartment, and the film segues, invisibly enough for it to be confusing, to another point in time entirely, in the immediate aftermath of their breakup. As we'll eventually figure out, this is in fact a flashback. And we'll never figure out which if any of the film's 17th through 32nd minutes take place in reality, versus the ones that obviously take place inside Joel's memories.

For that is, of course, the film's hook: after two years of dating, Joel and Clementine had a terrible fight and broke up, after which she went to a company called Lacuna, Inc.* which specialises in erasing unwelcome memories. Joel only finds out about this after confronting the couple's friends, Carrie (Jane Adams) and Rob (David Cross), who reluctantly show him a card explaining to everybody who knows Clementine that she has absolutely no memories of Joel's existence, and no-one should ever speak to her about him. Aghast and distraught, Joel signs up to receive the very same treatment, and the rest of the movie, takes place on the night that Lacuna's top man, Stan (Mark Ruffalo), and its clearly not-top man, Patrick (Elijah Wood) come to Joel's apartment to erase Clementine, which he experiences in the form of out-of-order memories coming to the fore and then dissolving, either in clean fades to nothingness, or through perplexing, discontinuous destruction and collapse, as Joel finds that he treasures even his painful memories too much to part with them, and begins fighting the Lacuna techs.

Thus begins quite a hefty meditation on the value of relationships, even toxic and dysfunctional ones, and the importance of strong memories, even painful and humiliating ones. On one level, this is just a puzzle: we see Joel and Clementine's love grow, solidify, and die, all out of order, and the film insists on our actively paying attention to piece it all together and figure out the whys of it. But there are puzzles and there are puzzles, and Eternal Sunshine is absolutely not the sort of movie where the rewards stop the second we crack its mysteries. On the contrary, the very fact that this is all presented obscurely is one of the key ways that the film draws us in. It is a way that we are more tightly aligned with Joel's own feelings about the relationship, since we experience the jumble of memories in the order he does; we are thus placed in the position of trying to figure out what the hell is up with Clementine as well as he does. And yet, because we are an audience in a movie, and we get to be clear-eyed and not so hung up on stupid little nonsense as he is, we can pick up on all the thing she's saying and thinking and feeling that Joel didn't appreciate the first time around. It helps that both Carrey and Winslet give two of the best performances of the 2000s and maybe the best performance of their respective careers, and that Winslet in particular is energised by a vastly more complicated character. She is, after all, playing a woman who deliberately obscures her personality to avoid being hurt, as filtered through the self-centered memories of a man who was already too much of a sad romantic to see her clearly, and she's also providing enough in her body language and tone of voice to let us in the movie see the things that Joel can't. That's the other thing the fragmentary structure does: it demands we think very hard about what we're watching, so we can connect it to other fragments later, which invites us to have a much more sophisticated understanding of Clementine's own insides than Joel possesses.

Still, this is ultimately a film about Joel's experience of the relationship, and his experience of remembering the relationship even more. The cinematography (by Ellen Kuras), editing (by Valdís Óskarsdóttir), sound design (by Eugene Gearty), and directing are inseparably intertwined in creating a highly subjective experience, with the film itself breaking down and violating the basic rules of cinematic language in concert with Joel's loss of his memory; long before we know what's happening there are moments where the lighting blanks out and shots are cut together messily, foreshadowing the elimination of those moments, and as the film starts explaining what it's up to, those tricks and far more sophisticated ones pile up. Eternal Sunshine is a hard film to parse, and unlike most films that invents its own language, it doesn't ever have a moment where it explains its rules to us: it simply collapses in on itself, blurring moments visually and aurally, causing us a sense of dislocation as viewers of a movie that approximates Joel's dislocation as one of the core elements of his personality is removed while he witnesses it. It is one of the great marriages of content and style of the 21st Century.

It's so exhilarating to follow along as the film plays with these ideas that it's easy to forget that Eternal Sunshine ever moves outside Joel's head, though it spends quite a lot of time there. Some of this is quite brilliant, like the tiny moment nodding to people using Lacuna to forget children (I think) and lost pets, different traumas that the film acknowledges as equally hurtful to Joel's. Some of it is not; the subplots in which Stan is dating Lacuna's receptionist Mary (Kirsten Dunst), who has an obvious crush on company founder Dr. Mierzwiak (Tom Wilkinson), while Patrick is using his insider knowledge to date Clementine have always felt oddly lumpy to me, an attempt to do parallelism that the film doesn't require and can't do anything particularly useful with (I concede that this is not the consensus opinion). All of it is casual and roughly naturalistic, the better to counterpoint the abstract, imaginative, stylistically dizzy scenes inside of Joel's memories. That contrast between fantastic staging and realistic cinematography is the thing I always think of most about Eternal Sunshine; it is a movie that romanticises love and then views it with blunt clarity, and that mixture is exactly what helps the film to its ambiguously hopeful concluding thoughts.