So I don't know too much about the Elder Scrolls themselves, apart from stuff I could find on UESP/TIL (and that book about them in Oblivion), but even there it's kind of hard to find information because every other page on those sites has the phrase "The Elder Scrolls" on it.

Either way, is it possible that the Elder Scrolls are just pages taken somehow from Jyggalag's library before it was burned? Dyus says that they predicted everything, including the Numidium and the rise of Tiber Septim - and since the Greymarch happens every era the time when the Library was around could have been a really, really long time ago before Jyggalag was trapped.

Nice try, but not even close.

Well, as MK said, the elder scrolls didn't come from the library. For one thing, think of them as the game itself. It tells a similar-ish story, but varies between users, much like ourselves, our mood, and what role we want to play. My nerevarine could have been a major ass, while you were a paragon of virtue. I may have killed Dagoth Ur, all of the Tribunal, and danced on their bodies while naked. You, on the other hand, may have allowed Vivec to live out his days. When one reads the scrolls, they tell of an event, but how the event occurs and is achieved differs between readers.

With Jyggy, practically everything was calculated to a 100% certainty from what I gather. However, if you ask me, when Mundus came about, his calculations ended up being 99.9%. In other words, uncertainty came around. Perfect order no longer became a concept, and was banished to become Sheogorath, the Sithis shaped hole, born from when Shor's divine spark was removed.

Now, as to where the scrolls came from.. :shrug: . I forgot. I just know they're not Jyggy's, and are pretty linked to Mundus from what we have seen.

I'm pretty sure this is correct within a margin of error. Others are likely to come in and point out what I lacked, what I got wrong, and have a more comprehensive explanation. Think of this as looking at Cliff Notes/Spark Notes.

I think the origins of the Elder Scrolls are obscure. However, they function by showing every alternative possibility of the future or a complete look at a moment in the past. So cutting and fearsome is this insight that the future seeing makes a reader go temporarily (and eventually permanently) blind. However, because it shows all probability, all it can manage is to have those who know what they say manipulate events to help boost one probability over another.

The Library of Order is the sort of "logicians nightmare prophecy," where if you know what it says it can be stopped by as little as a single step. Jyggalag, having no originality, cannot comprehend it, or that a person would think of a way to break the predictions. There is only Shezzar to thank for that, because when he made Mundus he created free will.

Which makes me think that, more than madness and order, the two are also free will and predestination. One cannot exist while the other does.