Every 1000 years, the earth, moon, and sun perfectly align to form a solar eclipse that is seen around the planet. During this time, the barrier separating this reality from the demon world break down, allowing demons to enter our world. During this short window, the demons cause death and destruction on a planet wide scale, toppling empires overnight. After 7 1/2 minutes, the eclipse ends and the barrier comes into place, forcing the demons back into their reality.

You would think that an event as wide scale and traumatic as this would be remembered by the world. There would be historical records of it happening by authors or writers, leaving behind articles or making references to it. This is how we have knowledge of ancient civilizations, like the Romans or the Greeks, who were great record keepers and left evidence of themselves for their future generations. However, civilizations that spring up after the eclipse lose knowledge of it. As generations pass, they lose knowledge of this event and no records exist of it happening, keeping it out of history books.

How could this be possible? Why would a world have no memory of an event as wide scale as this?

  • 6
    $\begingroup$ I presume this isn't our Earth? Total Solar Eclipses: How Often Do They Occur (and Why)? It is a popular misconception that the phenomenon of a total eclipse of the sun is a rare occurrence. Quite the contrary. Approximately once every 18 months (on average) a total solar eclipse is visible from some place on the Earth’s surface.. space.com/…. $\endgroup$ – chasly - supports Monica Jul 1 '20 at 11:08
  • 2
    $\begingroup$ In addition to the astronomical problem, students of history would notice multiple civilization collapses happening on a regular schedule, and try to find out why $\endgroup$ – Patricia Shanahan Jul 1 '20 at 11:17
  • $\begingroup$ MiB agent #: "yo ya think our new recruits up to da job?" Agent $: "this is their problem since the beginning, why should we have da clean up this human shit." $\endgroup$ – user6760 Jul 1 '20 at 12:36
  • 3
    $\begingroup$ @chaslyfromUK It would, however, be basically impossible for a solar eclipse to be visible to the entire planet, given that it's night on half of it. Now if you're on a fictional world that has all of its inhabitable land on one side (say, nothing but ocean on the other side), it might be possible. (Though you might still have some sailors who would miss the eclipse because they were in the middle of the ocean...) $\endgroup$ – Darrel Hoffman Jul 1 '20 at 20:45
  • 3
    $\begingroup$ it could be deliberately banned and erased from memory by a dictatorial government. $\endgroup$ – njzk2 Jul 1 '20 at 21:07

I suggest reading Isaac Asimov's 1941 novelette "Nightfall". It is very similar to your plot, depending on an eclipse that happens once every 2,000 years causing a global catastrophe. Civilization never lasts more than 2,000 years before collapsing. Each time, the eclipse fades into myth and religious texts before the cycle repeats.

The story follows a group of researchers who have combined religious texts, recent research into gravity, and evidence of previous civilizations having collapsed. They think they understand what goes wrong, and try to preserve knowledge across the collapse that is about to happen.

The story contains some ideas on how knowledge is lost, partly in the immediate reaction and partly through the passage of time.

I hope many who have not already read "Nightfall" will do so before reading the spoilers. Science Fiction Writers of America selected it as the best science fiction short story written before 1965.

Spoiler alert! Pass mouse over the following.

The key problem is that civilization has to start again at a very low level, after each period of chaos. The scientists are trying to preserve knowledge and carry it forward giving the next cycle a head start. There are several groups opposing the effort.

The Cultists have built a religion around interpretation of the Book of Revelations, which apparently attempts to describe the phenomenon, and preserves a memory of stars.

There is a skeptical newspaper reporter who has been writing columns debunking the claim that civilization is about to end.

That prediction has caused an economic and stock market collapse, making ordinary people very angry.

All this is in a cycle in which archeology and astronomy have progressed to an unusual degree so the scientists think they know what to expect. Highly relevant to the question, there is a twist that takes the place of the demons. The planet is in the middle of a large and active giant cluster. With all the suns set or eclipsed, they see tens of thousands of bright stars. The realization of the size and grandeur of the universe hits suddenly in minutes, not as something learned and understood over centuries. The Book of Revelations had tried to warn, but the scientists had thought it was exaggerated.

  • 1
    $\begingroup$ It would be better if you put some of those ideas in the answer, so that one could retrieve them here without having to fetch and read the book. You can use use the spoiler tag in case you don't want to ruin the fun of reading the book $\endgroup$ – L.Dutch - Reinstate Monica Jul 1 '20 at 12:01
  • 1
    $\begingroup$ First, I need to learn how to use the spoiler tag. I don't want to spoil one of the best science fiction stories of all time for those who have not already read it. $\endgroup$ – Patricia Shanahan Jul 1 '20 at 12:19
  • 4
    $\begingroup$ I've edited your answer to include a dummy spoiler. This will show you how to do it. $\endgroup$ – chasly - supports Monica Jul 1 '20 at 12:30
  • 1
    $\begingroup$ Another way to show spoilers is to use Caesar Cipher rot(13). This can easily be created and recovered using online resources. See here for a website .v2.cryptii.com/caesar/rot13 -- Instructions: Clear text from the left hand pane and type your plain-text. The code appears on the right. To decode, type the coded version on the left and plain-text appears on the right. This method is used routinely on Puzzling Stack Exchange to avoid giving away answers, but you'll probably have to explain it here. Puzzling is here: puzzling.stackexchange.com $\endgroup$ – chasly - supports Monica Jul 1 '20 at 12:40
  • $\begingroup$ I have added spoilers, but strongly urge reading the story. I am familiar with Rot(13) from USENET, but did not know it was still being used. The spoiler tag seems simpler and needs less explanation. $\endgroup$ – Patricia Shanahan Jul 1 '20 at 16:19

The old tales aren't taken seriously because science wasn't and still isn't very advanced in your civilisation.

The Greeks kept records but they made little distinction between actuality, heroic tales and the activities of gods. The current scientists might say, "Oh well, something might have happened but maybe a volcano erupted and spread ash across the skies." Note that science would not be as advanced as ours because if they understood about orbits etc., scientists would be able to predict that an eclipse was going to happen.

There is a big frame challenge here.

Astronomically you are going to have a very hard time justifying this scenario. For the shadow of a moon to completely cover a planet would mean that the moon would have to be bigger than the planet!

In fact you would have to have your people live on the moon, then they could be eclipsed by the earth.

Actually we are eclipsed from seeing the Sun every night, that's why it goes dark.

For anyone with even a little scientific knowledge to believe your world you would have to design a very unusual solar system. I'm not even sure it is possible.

  • 8
    $\begingroup$ Isaac Asimov's Nightfall does depend on having a very unusual solar system. $\endgroup$ – Patricia Shanahan Jul 1 '20 at 11:54
  • 2
    $\begingroup$ "The Greeks kept records but they made little distinction between actuality, heroic tales and the activities of gods": I sincerely hope that this is intended as some sort of British humor. Most certainly Greek historians made a very clear distinction between real stuff, legendary stuff, and mythological stuff. We have zero problems reading, for example, Xenophons Anabasis and distinguishing between stuff which actually happened on one hand, and legendary and mythological stories on the other. (What they didn't really do is make a clear note of their sources for supposedly real stuff.) $\endgroup$ – AlexP Jul 1 '20 at 12:59
  • 3
    $\begingroup$ @AlexP They really didn't start doing so until Herodotus, and even then despite trying to stick to just the facts Herodotus included a lot of weird stuff that was folkloric at best (e.g., re-interpreting the myth of Europa as a historical event) or because he was way too trusting of secondary sources he couldn't cross-verify himself (i.e., giant ants that dig gold). What an ancient Greek would consider plausible is very different from what a modern person would. $\endgroup$ – user2352714 Jul 1 '20 at 17:35
  • $\begingroup$ @user2352714: And please who was keeping historical records before Herodotus? Speaking about the imprecision of historical records before Herodotus is like speaking about the unreliability of steam locomotives before Robert Stephenson. $\endgroup$ – AlexP Jul 1 '20 at 17:38
  • $\begingroup$ @AlexP The point is Herodotus, who was the first person to care about the difference between folklore/hearsay and verifiable fact, only published Histories halfway through the traditionally defined Greek Classical Era (430 B.C. in a period typically defined as spanning 510-323ish B.C.), and even he published a lot of stuff that modern audiences would consider supernatural or unreliable due to the way he collected evidence. So for half the Classical Era at minimum most people weren't making much of a distinction between history and story. $\endgroup$ – user2352714 Jul 1 '20 at 23:13

The demons are so traumatic and out of the ordinary that many survivors convince themselves that it didn't happen. They blank out the actual demons, or think they are hallucinations stemming from the trauma. Possibly the magic of the demons adds to the effect.

Discussion of the demons might be regarded as poor taste, or even actually dangerous. "Speak of the devil" is proverbial even in this world, but in that one, superstitions might spring up very quickly.

Furthermore, the tales DO get passed down -- mostly orally because the demons have trashed your ways to pass them on in writing -- and get written off as obvious myths because the demons have clearly impossible powers and traits.


Adding a non-fiction perspective to Patricia Shanahan's excellent answer

It's believed that something like this has happened, multiple times. In and around Mediterranean around 1177 BC in the span of a few short years the Minoan culture vanished, as did what's now believed to be several cultures further west disappearing entirely, known collectively as the Sea Peoples.

I this excellent video Eric Cline discusses in great detail the who, what, how, and why of it.

A similar complete loss of civilizations happened around 800 AD during the Classic Mayan Collapse when another complex network of civilizations stretching perhaps as far north as trading partners in North America completely disappeared.

In both of these cases, the collapse of civilization was so total that many of the worst-hit cultures are lost completely. No distinct memory of them remains. Even the cultures that "survived" didn't wholly.

TL;DR What's the Point?

These total collapses of civilization had some things in common:

  • A broadly distributed supply chain of essential goods and services
    • Takeaway: as shock-tolerant as the system might be, no culture retained to itself all of the knowledge and tools to supply essential needs (food, manufacturing)
  • Long term stresses on the supply chain (drought + famine + disease)
  • One or a few shocks that might have, by themselves been survivable (earthquakes, eruptions)

Which lead to:

  • Large-scale migrations of peoples in the worst-hit areas to once less afflicted (or perceived to be less afflicted)
  • Governments closing the borders to waves of refugees further stretching their already badly-stressed resources
  • Mounting frustration by refugees and governments alike, leading to wars and riots


In a very short amount of time, several cultures were geographically stacked in a very small region "super melting pot". Language and culture evolved and blended into something unrecognizably new in an incredibly short time. Old culture, language, writing, and science all faded away.

How to Apply to Your Situation

  • The long term stress can be your eclipse. It's only 7 $1 \over 2$ minutes long, but no one knows when (or if) it will happen again. I imagine people groups worst hit by the eclipse will hear stories of peoples that fared better, and start picking up in large waves to emigrate. Further stress might be some other issues going on at the time: one of more epidemics, famine, drought.
  • Short term stresses can be earthquakes, fires, volcanic eruptions. The people might freak thinking the eclipse is about to happen again.
  • The global supply chain breaks down. You can't get your corn from Indiana or pharmaceuticals from Asia because the farms and factories have been abandoned. No one is minding the satellites because the monitoring stations in California are empty, and no one is available to fix a simple problem like a popped breaker, keeping telecommute away. Local governments don't know how to grow crops or compound medicines and possibly make things worse by trying because "it's easy" (see the Cultural Revolution)
  • Eventually, things stabilize in super-densely packed urban centers containing dozens of cultures. They are ungovernable. The people work out amongst themselves new languages and ways of living with one another. Pragmatism and survival is prioritized over luxuries like education.
  • Society becomes wholly illiterate. It will eventually re-invent writing.
  • Even the generation born after the eclipse, not knowing anything else, will have trouble believing their parents' stories about how this all came to be. The story will be poorly kept, probably embellished greatly, if retained at all.
  • 4
    $\begingroup$ The modern civilization might even mistake the demons for someone like the Sea Peoples, thinking that "oh, these people just demonized the invading culture as non-human" when they were really facing actual demons, and if there was no physical evidence like armor made for a non-human body nobody would know any different until it was too late. Archaeologists rationalize purported supernatural occurences like that all the time. $\endgroup$ – user2352714 Jul 1 '20 at 23:22
  • $\begingroup$ Given that part of the Rosetta Stone was written in 196 BCE in hieroglyphics, the statement that the written Egyptian language disappeared shortly after the Bronze Age collapse a thousand years before is clearly wrong and obvious after a few seconds of thinking about it. The Egyptians wrote in hieroglyphics well after that point, right into the Roman era with some dating as recently as the 4th Century CE. $\endgroup$ – Keith Morrison Jul 2 '20 at 15:54
  • $\begingroup$ Hmm. I wonder when society will again rely on extensive trading networks for fundamental resources and what kind of disruption might occur (cough cough) $\endgroup$ – user253751 Jul 2 '20 at 16:35
  • $\begingroup$ @KeithMorrison removed those parts. $\endgroup$ – James McLellan Jul 2 '20 at 19:07

The answer is already there in your question: demons.

According to the Bible, several thousand years ago, the entire planet was under water. Most modern people refuse to believe this because it suggests a supernatural explanation.

Demons are a silly superstition that only scientifically backwards people could possibly believe. We're "enlightened" these days and don't accept such obvious nonsense.

Seriously, just do a little digging into how willing most people these days are to accept "supernatural" occurrences, and you'll have all the answer you need.

For bonus points, you probably have a religious fringe that does believe in what really happened (and gets laughed at by the rest of the "scientific" community). Boy, are they going to be smug when it turns out they were right all along. Assuming, of course, they don't all come down with an acute, demon-induced case of discorporation.

To expand on this a bit... (Please try to keep an open mind and try to avoid falling into politics; there is a relevant reason why I'm trying to explain this, which I will summarize at the end.)

What a lot of people don't understand about "science" is that your interpretation of the evidence is extremely dependent on your fundamental axioms (dogma). Creationist dogma is "the Bible is probably accurate". From this starting point, they are able to build a cohesive explanation of science, including plausible (to them) explanations for "evolution", the fossil record, and radiometric dating. This framework is capable of making useful predictions and even addresses some evidence that is problematic for uniformitarianists ("dark" matter, cosmic temporal horizon, certain inconsistencies in radiometric dating).

Uniformitarianist dogma, on the other hand, can be summed up as "God can't exist". This is not an evidence-based conjecture, it is an axiomatic assertion that uniformitarianists will not allow to be challenged. Because of this philosophy, they reject certain hypotheses that a creationist would take as self-evident, and are able to build their own, completely different, but still plausible (to them) view of the universe. This framework is also capable of making useful predictions and even addresses some evidence that is problematic for creationists (radiometric dating, apparent age of the universe).

Obviously, these can't both be correct, and yet good luck trying to convince either side that they're wrong. For that matter, try going after a real nut (flat earth, moon landing hoax, etc.) and see just how effectively they respond to evidence that is contrary to their belief.

The point, and the relevance, is that humans are really good at interpreting evidence to fit their preexisting dogma. For the purposes of this question, if humans somehow arrive at the dogma that demons can't exist, it doesn't matter what evidence there is to the contrary; they will find a way to explain it that doesn't violate their prior dogma. Their ability to do so is isn't conjecture, it is thoroughly demonstrated in real life. (It will help if there aren't a lot of written records immediately following "the event", but even that is no guarantee. Just look at how many cultures have a flood myth, and ask someone at random if they believe there was a global flood at some point in Earth's history. Now replace "flood" with "demon invasion".)

The secondary point and corollary is that you can take a mountain of inspiration for this from real life. Depending on where you want to take the story, it could easily become a social commentary for oppressed minorities, casting the "demon deniers" as the "scientific" majority and the "demon believers" as a marginalized, ostracized, and even persecuted minority. There is more than enough real world experience to draw on for inspiration.

  • 1
    $\begingroup$ People don't believe in the supernatural because there are only anecdotal experiences of supernatural occurrences, and supposed supernatural occurrences have not left behind the supporting evidence that would exist had they really occurred (i.e., they did not actually happen). Neither of those apply to this event, which is witnessed by the entire planet, and leaves a tangible trail of evidence in its wake. I don't see how the whole world would wake up the next day and decide "that didn't happen", rather than concluding "that happened but I don't understand it". $\endgroup$ – Nuclear Hoagie Jul 1 '20 at 14:43
  • 1
    $\begingroup$ For a scientifically-minded people, this event indisputably occurred and does not fit their worldview at all. It will be one of the best-documented and well-studied events in their history for precisely that reason. Science currently does not concern itself with the supernatural because there isn't any credible evidence that needs further study in the first place. When scientists make well-documented, reproducible findings that do not fit current theories, those become fields of intense study, rather than being ignored as "supernatural". $\endgroup$ – Nuclear Hoagie Jul 1 '20 at 14:50
  • 1
    $\begingroup$ Wrong. People don't believe in the supernatural because modern "scientists" are dogmatically opposed to believing in the supernatural. There is a huge pile of evidence that can be interpreted as supporting the Bible if you are willing to accept such an explanation. Modern "science" is not. Conversely, look at any of the folks that deny climate change, or the moon landings, or that the Earth is round. Dogma is not swayed by evidence, no matter how persuasive. A dogmatic attitude that "demons don't exist", for which real life gives precedent, will quite suffice for the OP's purposes. $\endgroup$ – Matthew Jul 1 '20 at 14:55
  • 2
    $\begingroup$ Science changes all the time to accommodate new evidence - see heliocentrism, the photoelectric effect, blackbody radiation, or general relativity. I don't see how you can compare a dogma like Flat Earthism that ignores or distorts evidence to a scientific dogma, which by definition, is based entirely on evidence and observation. The whole idea of science is predicated on the notion that if observation does not fit the theory, it's the theory that's wrong. You can certainly have a dogma of "demons don't exist", but it's not at all a scientific dogma if it ignores widespread evidence of demons. $\endgroup$ – Nuclear Hoagie Jul 1 '20 at 15:48
  • 1
    $\begingroup$ What if, one day here on earth, early in the morning, fairies, goblins, kobolds, trolls and all the other assorted wild things came out to play, and wrecked havoc. Then, again, they disappeared the next night, never to be seen again. For many hundreds of years. Now, what would happen tomorrow? Would CNN downplay it as mass hallucination? After some months, it would simply be forgotten. $\endgroup$ – CGCampbell Jul 1 '20 at 23:10

Demons have a propensity of attacking more advanced civilizations.

Cities and even standalone buildings like farmsteads and temples would see a thorough destruction, while indigenous people who don't build any permanent structures may not see any demons at all. As a result, every civilization which has reached the level of cities (and literacy) would get wiped out. Its buildings would become ruins suitable only to quarry stone, and its remaining written records would be illegible for anyone from subsequent generations.

But humanity as a whole would survive just fine. New people would occupy old lands and, given time, raise their own cities and develop their own writing. But there would be no accounts of the past event - only vague legends and horror stories to spook naughty children.

If the new civilization has a chance of advancing into industrial age and develop archeology and study extinct languages, it would have a chance of figuring out what exactly had happened. But before that, the new civilization won't even know that there was any kind of global event.


Don't speak the name of the Devil:

Many cultures have prohibitions of speaking of or naming evil beings.It is believed that these beings are called up or their attention drawn to the speaker. Why not apply this on a global scale? After all, when faced with clear proof that demons exist, and another clear prohibition not to speak their names, who wouldn't assume some idiot said Chutulu's or Satan's name and unleashed hell on Earth? Given demons, it might even be true. Perhaps speaking of them causes lesser manifestations of these evil entities. Given these minor demons (possessions, etc) and the motivation of demons to silence anyone speaking of them, historians would be plagued by evil and curses, and the locals would NOT view historians kindly. What if that historian wrote the names down? Burn those books, and maybe the historian for good measure.


This race of humans might be very aggressive and opportunistic. They would constantly be warring amongst themselves for territory and domination, making accurate record keeping difficult as it is near impossible to stay out of the conflicts. This is how knowledge can easily be lost to future generations (the library of Alexandria springs to mind).

When a large scale demon attack happens, the current ruling faction will be most represented throughout the world, and therefore be hit hardest as they have the largest military presence. Other factions could easily rise up and seize this opportunity and overthrow them in their weakened state. If successful they could claim the victory as their own to establish dominance, denying the demons had anything to do with it, or even exist in the first place.

To further their dominance they might actually aggressively purge any scholars recording the demon attacks to prevent the truth coming out undermining their glorious victory. A civilisation as hell-bent (pun intended) on keeping the truth a secret to further their own agenda can be very successful in doing so, if they are willing to kill for it.


The ancient civilization blames it on the gods. As a result, a modern, secular society does not believe in it and believes it to be a myth much like the Biblical flood.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.