If you read the writing on the wall, they tell a story about the summoners using the great crystal to summon in their experiments, and they brought forth a terrible evil that threated to destroy the world. They ended up using the great crystal to seal him within it, and they broke the crystal into four pieces so there would be no chance of his return.
Who on the what, now? I really need to play this game again.

Quote Originally Posted by jammi567 View Post
But surely the theory that fills in the most plot holes without thinking of too many other questions is the best one?
The problem is that, despite how well it may work, there's no way of knowing if it is right. It's like Lunar said- what Square put in the game for the player and what the player makes from the game are different sometimes.