The facts of the history related by Jodorowsky's Dune are thus: in 1975, Chilean director Alejandro Jodorowsky, having made in quick succession the films El topo and The Holy Mountain, had become a massive celebrity among the art film set, virtually inventing the concept of the midnight movie. He was in a position that few directors reach, and virtually none with such radical artistic amibitions, which is that he had a blank check to do whatever he wanted. And, largely on the spur of the moment, he wanted to make a film of Frank Herbert's massive, indescribably important science fiction novel Dune.

Over the next couple of years, Jodorowsky assembled a dream team of designers, including French graphic artist Moebius, American effects designer and filmmaker-of-all-trades Dan O'Bannon, and British illustrator Chris Foss, and proceeded to build his universe. And what a universe it was! Jodorowsky's Dune was ambitious beyond the scope that filmmaking in the mid-'70s was even slightly capable of, an hours-long epic experience full of effects work that's frankly impossible to imagine carrying off without recourse to animation and computers. No studio was even a little tempted to take on such an expensive proposition whose full-throated commitment to avante-garde spirituality made it a guaranteed money loser, and so the film died, while Star Wars came along and re-shaped science fiction filmmaking its own image. But even in death, Dune begat marvels: its massive book of concept art has influenced decades of subsequent films, either implicitly or directly. For one thing, O'Bannon would not have written Alien without Jodorowsky's Dune, nor would H.R. Giger (who had never worked in film before Jodorowsky lassoed him) have designed its titular beast. And that alone would change the fantasy and sci-fi landscape in a great many ways.

So that, anyway, is what happened. Jodorowsky's Dune is about two things: one, it tells that story, at length and with an easy, stretched-out attitude. Two, it tries to communicate, in some small way, what that film might possibly have looked like, throwing concept art at the camera every so often and animating it to suggest, in the broadest sense, the scale and visual splendor of the film that wasn't. All of which is interesting enough, but only really to sci-fi buffs and film historians, and director Frank Pavich isn't a very flexible or imaginative documentary maker. Jodorowsky's Dune has the aesthetic of a TV episode, intercutting wave after wave of talking heads with not nearly as much visualisation of Jodorowsky's dream project as one could easily hope for, since what we see of the film looks absolutely jaw-dropping.

In short, Jodorowsky's Dune could easily be written off as slack, workaday filmmaking, more of a DVD special feature than a standalone motion picture, except for one thing: it has, in Alejandro Jodorowsky himself, an amazing, one-of-a-kind storyteller, whose enthusiasm for the film he didn't get to make is electrifying and magnetic, even after almost 40 years. The 84-year-old director (who came out of retirement as a result of his involvement with this documentary, making The Dance of Reality in 2013) positively glows with enthusiasm and passion as he describes the philosophy and spirituality behind his filmmaking career, and the consciousness-changing experience he wanted his Dune to be; as he talks about his experience finding Moebius and Giger, he feels like a genuine art enthusiast proudly sharing his interests and insights. He even feels smugly, relatably human when he talks about his shameful joy at finding out that David Lynch's film of Dune from 1984, produced by Dino De Laurentiis, was a dismal, incoherent misfire. Hearing Jodorowsky relate his life and tell the story and themes of his Dune is an absolute privilege; it's like finding yourself seated at a long dinner next to the most animated raconteur you will ever meet, and as much pleasure as Jodorowsky's Dune offers in showcasing the images of the failed film, the pleasure in getting to listen to Jodorowsky and watch his amiable, excited face is far, far greater.

The net experience, then, is a good one, though there are some pretty rough spots throughout - in addition to his lack of formal imagination, Pavich has some questionable instincts. The most dubious misstep is the choice of interview subjects: director Nicolas Winding Refn makes at least a kind of sense, as he was given a tour of the Dune concept art book by Jodorowsky himself, and has solid insights as a result, even when he starts to wax rhapsodic about the transformative possibilities of this movie and the fear in Hollywood that shut it down (the fear of losing a shitpile of money, yes; the fear of transgressive art, probably less so), suggesting a bit more fannish enthusiasm than critical awareness. Showing even less critical awareness: film critics Devin Faraci and Drew McWeeny, a rather odd pair of experts to rely on, whose ability to form links where they don't belong (e.g. "this somewhat unexceptional shot set-up could only mean that this director saw the Dune material and copied it!") doesn't always come close to passing the smell test. Pavich waves through their theories without hesitation; he's clearly smitten with his material as well, and doesn't appear to suppose that anybody on any side of the camera could do with a little bit of cold objectivity.

This doesn't make Jodorowsky's Dune any less enjoyable, but it does make it less informative, or at least makes it feel less trustworthy, which amounts to the same thing. It's a boosterish film, a documentary only because it reveals a history (and a worthwhile history at that), but certainly not because it has a strong journalistic spine. It's a skillful sales pitch for a film that cannot exist, and which gives considerable joy to those involved to remember as the best work they almost did; their enthusiasm is contagious, but there's still a kind of shallowness built into the project. While Jodorowsky's Dune does a fine job of suggesting that Jodorowsky's Dune would have been marvelous, and possibly even the great work of spiritual philosophy the director wanted, but it never quite admits that maybe the thinking about it was the best part of all, and the execution might not have been up to the inspiration. Still, the inspiration is pretty damn inspiring for all that, and Jodorowsky is such a blast that it's easy to want to be on his side. Sometimes, hearing a yarn spun with energy and commitment is more important than all the big budgets and enormous scope in the world.