It is interesting that this secular and ecclesiastical principle also has theological counterparts – if we consider subsidiarity in the larger sense, i.e., in Creation. St. Thomas Aquinas, following Gregory the Great and Pseudo-Dionysius in their descriptions of the ordering and interrelationships of the nine choirs of angels, discusses the ways in which the higher orders share insights and coordinate the operations of divine providence with the lower orders. According to Catholic tradition, angels are not only entrusted with the care of each individual human being at birth, but also assigned to parishes, cities, and nations. Aquinas (Summa I, 108,) suggests that the divine government of “peoples and nations” is entrusted to the third order of ministering angels, the “Principalities.” As a possible instance of this arrangement, the angel who came in 1916 to prepare the three visionaries at Fatima for the apparitions of Our Lady the following year, told the children that he was the “guardian angel of Portugal.”
Apparently the care of angels is not completely “top down” but involves some interaction and discussion. For example, in Daniel 10:13, the angel Gabriel explains to the prophet Daniel that the delay in response to his prayer for his fellow Israelites is due to the fact that “the Prince [angel] of Persia resisted me for 21 days.” Aquinas explains this development in the Summa in his article (I, 113) on “Whether there can be conflicts or discord among the angels”: “The ‘prince’ of the kingdom of the Persians,” writes Aquinas, “was an angel who was opposing the liberation of the Israelites…. It happens sometimes that in various dominions, or in various individuals, pros and cons obtain…. The angels are said to ‘resist’ each other insofar as they need to consult the divine will about the merits or demerits….”
I'd never heard of the subsidiarity among the angels before reading it here. Google yielded this:
Way back, before the creation of the universe, God created the angels. Though we are somewhat familiar with the so-called nine choirs of angels, suffice it to say that the two highest, noblest, and most-powerful of the choirs are the cherubim and seraphim while the two lowest, bottom-most choirs are called the archangels and angels. The latter two are the angels we most commonly read about in the Bible. When God speaks to individuals through His angels (which means messenger), He does so with the lowest of the angels. But God also turned to these low angels at a very important time: the Fall of Lucifer.
Lucifer was a seraph, the highest and most powerful of all the angels. Now when Lucifer rebelled against God, God could have shown is power and vaporized Lucifer – but instead he went down to the weakest of the angels and used them to cast out Lucifer and his followers (which amounted to a whopping one-third of the angels). What’s more, God created man – a being far lower than the lowest angels – to finish what Michael and his angels begun! The point I am trying to make is that God is a staunch practitioner of something the Church calls subsidiarity. The Catechism defines subsidiarity in the following way:
The teaching of the Church has elaborated the principle of subsidiarity, according to which “a community of a higher order should not interfere in the internal life of a community of a lower order, depriving the latter of its functions, but rather should support it in case of need and help to co- ordinate its activity with the activities of the rest of society, always with a view to the common good” (CCC 1883, quoting Pope Pius XI).In other words if a lower form of order can do the job, don’t interfere. In the case of the angels, what seemed impossible was accomplished to the great glory of God and his lowly angels.