Jack Kirby’s The Eternals, which celebrates its 45 anniversary this week, may be the comic that demonstrated the limits of the Marvel Universe — and that is meant as a compliment.

The history behind the creation of the comic is relatively well-known; alongside an enthusiastic run on Captain America, Eternals marked the return of Kirby to Marvel after his five year stint at DC, where he’d created New Gods and the entire Fourth World Saga — arguably the creative peak of his career, which had already lasted four decades at that point. (Kirby started in comics young, in 1936; he was just 19 years old.)

The failure of New Gods had clearly left its mark on Kirby, and even though he continued to move forward with new ideas and new concepts, as he was seemingly compelled to do — he went from the cancellation of New Gods and The Forever People to creating The Demon and OMAC almost instantly — there’s more than a little of the cosmic DNA of the Fourth World to be found in Eternals, combined with no small measure of his earlier work with Marvel’s own Inhumans, as well. (Notably, the Inhumans, the New Gods, and the Eternals as concepts all see Kirby creating an entire cast of superpowered characters with elaborate, beautifully designed costumes on both sides of a battle that comes with its own complicated backstory, made from scratch.)

If New Gods had seen Kirby attempt to create a modern mythology complete with new deities for the modern world, however, The Eternals had him invent an entirely new backstory for humanity that folded in pre-existing religions and evolutionary processes, something that would have already seemed bold even without his also putting a time limit on humanity’s very existence, courtesy of the series’ central Macguffin: the return of the space gods responsible for life on Earth to judge whether or not we’d done enough to be worth keeping around.

To call The Eternals ambitious would be an understatement. Even ignoring the genuinely breathtaking ideas hidden inside the ideological framework for the series — humanity is just one of three tribes created not by any existing deity, but a collective of robotic-looking aliens, with the Devil himself belonging to another of the tribes, the imperfect “Deviants” who represent the worst of us; the titular Eternals, by contrast, are superpowered beings that are as good as the Deviants are flawed, and are the basis for the majority of figures of the world’s established religions, with we human schlubs stuck in the middle, a mixed-up collection of good and bad — the execution of each issue underscores how excitingly restless Kirby had become as a creator. Just the opening double-page splashes from the early issues of the series work on a scale few other comic artists could even dream of, never mind achieve.

Unfortunately, the scale of Kirby’s ambition might have been the series’ undoing.

There were early warning signs, perhaps; the series title was changed between its announcement and launch, going from the initial Return of the Gods — a title that acknowledged the debt Kirby owed to Erich Von Daniken’s then-popular book Chariot of the Gods — to the more benign The Eternals. The title of the second issue’s story was similarly changed ahead of time again, as Kirby’s second attempt to use “Return of the Gods” was replaced by “The Celestials,” after the space gods returning to Earth; the title, it seemed, was cursed… at Marvel, at least. A year after The Eternals launched, DC would revive Kirby’s new Gods with a new creative team, retitling the series as Return of the New Gods in the process. It’s unclear if this was coincidence or a subtle dig.

Once the series was up and running, it was clear that Kirby’s vision wasn’t meshing with the Marvel Comics of the era — one that was, even in the mid-70s, far less restrictive of creative freedom than the Disney behemoth of today. It wasn’t simply that his series didn’t seem to co-exist with the shared universe of the Avengers, X-Men, et al, a complaint from editorial that led to a Hulk cameo in later issues… even if the Hulk in question was a robot built by fans of the character, in an unexpected metatexual moment.

By its very nature, The Eternals redefined everything readers knew about the world they were reading about, being blasphemous not only in a literal sense — there is no God, only giant aliens — but, perhaps more damagingly, in the Marvel sense, with each member of its cast more impressive than the regular Marvel heroes, and entirely disinterested in them at the same time. It was a comic published by Marvel that felt as if the Marvel Universe was surplus to requirements.

It couldn’t last, of course. After 19 issues (and one annual), The Eternals was cancelled with a story that failed to resolve any of the larger questions raised by the series; Kirby would move on to create Machine Man and Devil Dinosaur for Marvel before leaving the company for good within a couple of years, and the Eternals themselves would go on to be folded into the larger Marvel Universe in a series of increasingly unfamiliar and unlikely maneuvers over the next decade or so, with each attempt making everything Kirby had created smaller and less interesting.

As things stand now, The Eternals is primed for the big screen as Marvel Studios’ big end of year movie, with a new comic book reboot already available in preparation. If experience is anything to go by, what audiences should expect is something that might use the names and occasional visual cue of Kirby’s original, but will carefully abandon the scale or intent of the original comic book, steering clear of any attempt to redefine religious icons or offer a new evolutionary model. It only makes sense; as with so many of Jack Kirby’s ideas, some things are too big for a shared universe.