In the 6th Century, Pope St. Gregory the Great wrote this:
"I say it without the least hesitation, whoever calls himself the universal bishop, or desires this title, is, by his pride, the precursor of Antichrist, because he thus attempts to raise himself above the others. The error into which he falls springs from pride equal to that of Antichrist; for as that Wicked One wished to be regarded as exalted above other men, like a god, so likewise whoever would be called sole bishop exalteth himself above others....You know it, my brother; hath not the venerable Council of Chalcedon conferred the honorary title of 'universal' upon the bishops of this Apostolic See [Rome], whereof I am, by God's will, the servant? And yet none of us hath permitted this title to be given to him; none hath assumed this bold title, lest by assuming a special distinction in the dignity of the episcopate, we should seem to refuse it to all the brethren." (Orthodoxwiki)
In the 19th Century, the Bishop(s) of Rome decreed this:
Wherefore we teach and declare that, by divine ordinance, the Roman Church possesses a pre-eminence of ordinary power over every other Church, and that this jurisdictional power of the Roman Pontiff is both episcopal and immediate. Both clergy and faithful, of whatever rite and dignity, both singly and collectively, are bound to submit to this power by the duty of hierarchical subordination and true obedience, and this not only in matters concerning faith and morals, but also in those which regard the discipline and government of the Church throughout the world...
...In this way, by unity with the Roman Pontiff in communion and in profession of the same faith , the Church of Christ becomes one flock under one Supreme Shepherd. (Pastor Aeternus)
How does a Catholic layman reconcile these two contexts?