Reflections of a stormy petrel

As has been said, a brilliant essay. The only thing I would add to it (and I'm sure you're well aware) is that the western church, and especially the Papacy, were not wholly unused to dealing with the idea and reality of state control of the Church before the 14th century. Most of the dealings of the eastern and western churches for many centuries had hung on the central and controlling power of the Byzantine Emperor over the eastern church, and his pretensions to a sort of universal quasi-papacy over the entire church. Justinian, to take one of the more drastic examples, seemed to think little of kidnapping Popes, calling ecumenical councils without participation by either the Pope or so much as a single Western bishop, and issuing religious condemnations at his whim, for whatever political or religious end he wished--and his actions were hardly an aberration, as the martyrdom of Pope St. Martin, the entire iconoclast controversy, and a hundred other examples would testify. The freedom of the papacy and the western church from Imperial control was not easily won.
Again, a brilliant essay. I've very much enjoyed and learned from your historical writings here, and I've even taken a stab at reading through your work on British history. Good stuff.