The deity at the center of the pediment on the temple of zeus at olympia (4.2.1), who brings order to the scene, is

I believe the correct answer is: Apollo.
 
The pediments of the Temple of Zeus at Olympia are some of the best surviving examples of early Classical Greek sculpture which were completed in 460 BCE. On the west pediment ('centauromachy' – battle between centaurs and the Lapiths) Zeus stands in the center on the east and Apollo on the west. But, Apollo is the deity who brings order to the scene as he is a deity promising to restore order as the deity of rationality and self-control.

The gregorian chant was a major cultural milestone in the middle ages. it was one of the first codified forms of music meant to be played as written, where previously it was difficult to mass-produce and disseminate any music. what's more, these chants were also some of the first examples of musical notation: the notes and bars of today's music sheets are a reflection of centuries of evolution beginning with these chants. it became official throughout the entirety of the catholic church, meaning that nearly all of europe followed this musical notation and styling.

That is true  i hope that : )