H/T to Charles Charles A. Coulombe
"Catholicism, as Orthodoxy, has, historically, regarded the monarchical institution in this light: raised up by Providence to safeguard the natural law in its transmission through history as that norm for human co-existence which, founded as it is on the Creator, and renewed by him as the Redeemer, cannot be made subject to the positive law, or administrative fiat, or the dictates of cultural fashion. Let us dare to exercise a Christian political imagination on an as yet unspecifiable future.
The articulation of the foundational natural and Judaeo-Christian norms of a really united Europe, for instance, would most appropriately be made by such a crown, whose legal and customary relations with the national peoples would be modelled on the best aspects of historic practice in the (Western) Holy Roman Empire and the Byzantine “Commonwealth” — to use the term popularised by Professor Dimtri Obolensky.
Such a crown, as the integrating factor of an international European Christendom, would leave intact the functioning of parliamentary government in the republican or monarchical polities of its constituent nations and analogues in city and village in other representative and participatory forms. As the Spanish political theorist Alvaro D’Ors defines the concepts, power — that is, government — as raised up by the people can and should be distinguished from authority.
Power in this sense puts questions to those in authority as to what ought to be done. It asks whether technically possible acts of government, for co-ordinating the goals of individuals and groups in society, chime, or do not chime, with the foundational norms of society, deemed as these are to rest on the will of God as the ultimate power of the shared human goal. Authority, itself bereft of such power, answers out of a wisdom which society can recognise."
Fr. Aidan Nichols, OP, Christendom Awake: On Re-Energizing the Church in Culture