I have a theory about the meaning of the of Ultimecia's clock puzzle: 'In the Garden Sleeps a Messenger'.
I think it's referring to the GF Diablos.
Here's why:
1) As I suggested in my 'Garden of Eden' thread, I think that the GF Eden is an organic version of a Garden. Hence she (and I think it's quite clear that Eden is female) is the garden of Eden.
2) Diablos' attack is called 'Dark Messenger'.
3) The Devil tempted Adam and Eve in the garden of Eden in the form of a serpent. Diablos is certainly demonic.
So I think the puzzle is an allegory about to the fall of man through temptation. It would certainly fit in Ultimecia's castle.
Or am I thinking about this too much?