The story of the Empress Galla Placidia deals with such things as system dynamics, the fall of empires, resource depletion, controlling complex systems and, yes, also a little about Christmas.
Her story seems like the plot of an adventure movie. She started as a princess, then she was prisoner of the Goths, then she became their Queen, then she was again their prisoner.
In the 5th century, when she came to power, the Roman Empire had been running out of reactants. It had been growing on the profits made from military campaigns but, at some point around the 2nd century, it had reached its limits. With no more easy conquests in sight, the Empire had to live on its own resources and it never really learned how to do that.
During the 5th century, what an emperor (or empress) could have done was to give to the events just a little push in the right direction. Don’t fight the change, ease it. It is the way of pushing the levers in the right direction. Could Placidia have done just that? Incredibly, perhaps she did.