It is the foundation upon which the Catholic doctrinal tradition is built and is captured admirably—especially in the final two paragraphs of the excerpt which I have bolded—in this article from First Things.

An excerpt.

Given that the evils against which he fought—totalitarian repression, unrestrained capitalism, sexual immorality, moral heresy, aggressive secularism, racist nationalism, and so on—still cause us such grief, it is striking that Pope Pius XI is little celebrated today. He is remembered for his denunciation of the Nazis, and for the Feast of Christ the King, which Catholics marked on Sunday. But something about him puts people off—perhaps his regal manner. When instituting Sunday’s feast, he taught that every individual, every society, is “under the dominion of Christ,” and that Christ’s Kingship must be recognized “both in private and in public life.” He believed, moreover, that human authority would be more respected if it reflected divine authority; and so, when passing on the teaching of Christ, he spoke and acted with a commanding, almost imperious, confidence.

Some of this was a matter of personal character. Even when he was plain Mgr. Achille Ratti, a respected paleographer and librarian, he did not flinch from a challenge: He and three companions became the first mountaineers to climb Monte Rosa (the second highest of the Alps) from the Italian side. Later, as nuncio to Poland, he asked permission from Rome to stay in Warsaw as the Red Army advanced. (Against all odds, the city held out.)

He carried the same bullheadedness into the papacy. In 1929, Bishop Liénart of Lille publicly donated to a fund in support of striking Catholic workers. There was outrage, and a few reactionaries protested to Rome: This bishop was some kind of Marxist! Pius responded by making Liénart a cardinal.

In 1937, the aging Pontiff issued Mit brennender Sorge, the most significant act of his continuous opposition to Nazism. It was not only the text—a long and ferociously undiplomatic rebuke—which stunned Hitler (for three days, reportedly, the Führer was so upset that he cancelled all appointments). It was also the cleverness with which the encyclical was smuggled into Germany, reprinted in hundreds of thousands of copies, and then read out at packed Palm Sunday Masses. According to the historian Henri Daniel-Rops, Pius made sure to publish a few days beforehand a separate encyclical, Divini Redemptoris, which denounced communism as a “pernicious enemy.” The result was that the Nazi press came out and said that perhaps Pius was a wise man after all, just days before Hitler would be condemned from the pulpit.

Pius’s character is not beyond criticism—he was given, says Eamon Duffy, to “towering rages which left his entourage weak and trembling.” But it was not only his personality which makes him such a definitive example, for good or ill, of the regal style of papacy. It was not as himself that he spoke so thunderously, but as a pope who wished to teach nothing that contradicted his predecessors. G. K. Chesterton seems to have had an intuition of this: On his visit to Rome in 1929, he received the papal blessing and suddenly understood why popes and kings used the plural “we.” (Until then, it had seemed a “senseless custom.”) For when Pius blessed the group, Chesterton realized “that it was indeed ‘We’; We, Peter and Gregory and Hildebrand and all the dynasty that does not die.”

Chesterton’s insight—that in Pius you could almost hear St. Peter and Pope Gregory the Great and so on—is crucial to understanding both Pius and the papacy itself. Pius’s words had such force because he tried to speak as a “We”: He bound himself to what had already been believed by Catholics throughout history and had been reaffirmed by his predecessors. He did not wish to deviate from that tradition by a millimeter.

Retrieved November 28, 2017 from https://www.firstthings.com/web-exclusives/2017/11/in-defense-of-regal-popes