Origin of the Enchiridion?

[Berethos]

The bare facts would certainly be sufficient for the short term, and might have even been sufficient in the long run...

But why deal with a might when some propaganda can further cloud the truth, extending the length of the ruse?

Also, changing how the government worked - from King to Church guiding four houses - would be a transition made easier by such propaganda.

So it wasn't a necessary act, but creating that compelling narrative made their long term goals easier to achieve.

Even with the ruse of a "just cause" fueling their society the people grew weary of the long years of war and needed a strict system of punishments to keep the populace toeing the line. A thousand years of just fighting a mad dragon for no other reason than they keep attacking could have led to questions long ago...questions that may have never stopped the war but possibly destabilized the government and weakened its power...

And this was a system put in place by those who broke a two century peace for power. That they'd do whatever they could to keep themselves in power makes sense.

On a different note specific to the Enchiridon - the Scholisticate quest line does seem to imply that the text is not at all immutable, and some parts of it are clearly treated as secondary to other parts even in present day Ishgard. While it may have changed little in a thousand years, that parts of it are held in lower regard and the duplicity of the founders of the system of government they used strongly suggests to me a clear timeframe for it to have been altered, possibly significantly.

[UAnchovy]

Would it have led to questions? Surely not any more than the version they did use? On the face of it, "we lived together with dragons for a while until they betrayed us because they're evil" is not less plausible than "we travelled into this region and then dragons came out of nowhere and attacked us because they're evil". Both versions contain the possibility of a hidden act of provocation that contextualises draconic aggression as well. If you were going to concoct a false history to justify the war against the dragons, wouldn't you try to concoct a false history that is more convincing or more morally compelling than the truth?

Similarly for other issues. You mention extending the length of the ruse. If I wanted a ruse to last a long time, wouldn't I prefer a ruse that is as consistent as possible with visible evidence, and which requires me to convince the fewest number of people of new facts? If I want a long-standing ruse, a lie that explains the existence of ruins from a time of coexistence is, ceteris paribus, preferable to a lie that doesn't. If I'm going to try to undertake a mammoth task like convincing thousands upon thousands of people that they (or their parents or grandparents) didn't really live alongside dragons after all, I should at least have a pretty good reason for trying something so difficult and so implausible. Here, it seems like it only weakens the overall integrity of the lie by introducing new inconsistencies into it.

It's particularly baffling, to me, because characters in-game portray the issue rather bizarrely. Take Aymeric's confrontation with Thordan VII in 'The Sins of Antiquity'. Thordan says, "No reparations shall ever suffice. This fact alone should serve as ample justification for our actions, yet some refuse to see it as such. For men like you, who yearn to commit themselves to a nobler cause, a more compelling narrative is required."

The first half of that statement is, in itself, perfectly reasonable. Nidhogg cannot be negotiated with. No reparations are possible. The only viable course of action is to fight back. Lies about history are irrelevant when you're dealing with a berserk dragon driven by hate. The second half is very strange. They need a more compelling narrative in order to convince idealists to defend the people of Ishgard? Surely idealists are already committed to defending the many innocent people of the city-state? Thus when we got to patch 3.3 and the Final Steps of Faith, there was no issue whatsoever of people like Aymeric or Lucia laying down their arms, or fighting only halfheartedly. They believed Thordan I was a monster who provoked the war, but they still laid down their lives to defend the people. The lie has no utility.

Yet Aymeric's reply to Thordan VII is little better. "This is how you protect our people? You have given us a lost cause! A death sentence! With your compelling narrative, you but doom our countrymen to give their lives for a lie!"

Really? I thought they were giving their lives to defend their home and their people. I don't think I ever saw the Dragonsong War framed as a battle to defend the honour of the noble King Thordan. That always seemed secondary to the issue that Nidhogg wants to kill everyone. Thordan VII hasn't given anyone a doom that they didn't already face. There is nothing Thordan VII could have said or done to prevent Nidhogg continuing the war.

Which gets back to the wider issue, for me. So, if I take most of the game's description of history at face value... a group of people concocted an extremely implausible lie and somehow convinced thousands of people of it, they obtained absolutely no benefit from this lie, and then the lie isn't even a more compelling narrative than the truth! If you tell the truth with the sole modification of claiming that Ratatoskr struck first, or perhaps that Thordan I uncovered evidence of a pre-emptive dragon attack, or somesuch, you get a story that is just as good for everything you want the lie to achieve, and you don't need to convince everyone of an implausible false history. Why lie about centuries if you only need to lie about five minutes?

Well, I can try to think my way around parts of this.

Firstly, as I said, this makes more sense to me if dragon-human cooperation was not actually widespread, and that most of the population of ancient Ishgard had relatively little contact with dragons. Secondly, I think you have to reject the idea that all this lie was produced by a small band of conspirators at the founding of the high houses. If much of this narrative grew in small accretions over centuries, it seems more logical. (For example, why would the founders of the high houses lie in order to say that Thordan I brought his people to Coerthas after receiving a vision from the Fury? That story is irrelevant to anything they might want to say about dragons, and obviously false if told to contemporaries of Thordan I who have been living in Coerthas for generations.) Over a longer period of time, however, there's more room for legends to grow. Thirdly, well, I would just be deeply skeptical of anything anyone tells us about that time. I don't think I trust Hraesvelgr's or Nidhogg's accounts. Dragons are an oral culture, without writing (EE p. 269), both of them have strong emotional biases, and memories can be unreliable. So when I encounter something that doesn't seem to make sense, I try to be open to the idea that perhaps the story is inaccurate. The church version is distorted and self-serving, but the dragon versions may be too. Piecing together the truth is very difficult.

Well. Feel free to consider me mad, or simply obsessing over minor issues. I will do my best to reach the Scholasticate quests, though. I'm sure they have a lot of fascinating additional content about Ishgardian religion and history.

[Berethos]

They need a more compelling narrative in order to convince idealists to defend the people of Ishgard?

Remember that those comments are coming from two individuals at the 1000 year old tail of a war that has defined their country since long before either was born - for one, continuing the war with as many advantages as are possible because there is ultimately no stopping the war (thus far anyway) is par for the course and certainly influences his beliefs, and for the other a good and noble cause is worth fighting for but so is seeking peace to end the suffering if it's possible, and continuing a war when peace is the most possible it has been in centuries is perhaps unthinkable...and thus influences his comments.

As for the founders...I think you're on to something regarding how much of what is seen/believed now was changed over the course of time, but I think it's worth considering that those who betrayed the peace after 200 years did so to seek power against those that were at the time not their enemy (I'd have to double check, but the Ascians may have had a small influencing hand in that belief...a nudge in the wrong direction if you will), so going the extra step beyond what was necessary to start a ruse if it would ultimately benefit them (and a nation fueled by fervor against an enemy would be a benefit) is certainly not unthinkable. Also, while logic might dictate that reducing the chance of the ruse being discovered to the smallest chance possible is the "correct" course this is meant to take place in an organic world where the characters don't always choose based solely on the most logical choice...especially if said logical choice didn't come with additional potential benefits in their eyes.

On dragons - they might actually be the most reliable when it comes to memories, believe it or not. They don't perceive time quite the same way...their "history is yet part of [their] present" in a way we can't comprehend. It does mean that they are influenced by emotional bias (potentially) to a far greater degree, but it also means that their memories of events are perhaps greater than any creature alive (at least for the Firstborn, like Nidhogg).

[UAnchovy]

To be fair as well, after that scene Aymeric does tell you that he thinks he expressed himself poorly. Perhaps he was kicking himself afterwards, and thought he could have made a better argument.

On what is believed now: I suppose my point is that it doesn't make sense, to me, for there to have been a single lie produced by a cabal of deceivers. Rather, we are probably dealing with a growing tissue of falsehoods. At the time of Thordan's death, perhaps all the founders of the high houses said was that the dragons turned upon them and slew their beloved king. They omitted, but didn't lie directly. Over the coming centuries, the details of Thordan's death passed into legend and were exaggerated. I don't know where the story of the elezen first coming to Coerthas came from; perhaps that was bundled into the Thordan story centuries later. To bring us back to the topic, this question about the textual history of the Enchiridion is fascinating.

On dragon memories, I am sure that they remember some things extremely clear, but as you say, their psychology is not like human (or elezen, hyur, etc.) psychology. Their history is part of their present. There's something Hraesvelgr says to Estinien atop Zenith that springs to mind. Estinien asked Hraesvelgr why he should believe Hraesvelgr's version of history over the church's, and Hraesvelgr answered, "What thou choosest to believe is immaterial. The betrayal that yet haunts mine every waking moment is no less than the truth to my kind. And Nidhogg meaneth for Thordan's people to suffer for this sin till the end of days."

That makes an interesting point about truth, I think. Nidhogg is not driven by a historian's truth, so to speak. He is driven by a personal and subjective impression of Ratatoskr's death, that he constantly relives. The impression of how it felt to know that his brood-sister was murdered by treacherous elezen is a permanent brand on his spirit. That's not something that can be changed. If, perhaps, someone were to find a reasonable historical argument that cast Thordan's actions in a new light, or even justified them, that would do nothing to alter this vengeful memory. Or neither is there any gift, apology, or recompense that could be offered that would alter the memory itself. Nidhogg is haunted by the sense of how it felt at that exact moment in history. The memory is eternal.

I find that much dragon behaviour makes more sense if their strongest memories are eternal in this way. It especially contextualises their tendency to brood. When you first meet Hraesvelgr, he is a broken dragon, sorrowfully reliving both his memories of Shiva and his memory of Ratatoskr's death. Or we can consider Tiamat, who is so consumed by the shameful memory of what she did to Bahamut that she is prepared to sit motionless in an Allagan prison for eternity. I would not not be surprised if the oldest dragons usually do end up consumed by memory. They are monomaniacal beings, whether Hraesvelgr for lost love, Tiamat for guilt, or Nidhogg for rage.

Anyway, so I don't think the elder wyrms lie to you, and neither do I think that their memories are false as such. But I think that their memories are of limited usefulness when it comes to discovering exactly what happened.