“We learn from the lessons of the office formerly composed for this feast, that the object of its institution was, as Urban conceived it, to obtain the cessation of the schism then desolating the Church. The Papacy, exiled from Rome for 70 years, had barely re-entered it, when hell, infuriated at a return which crossed all its plans, had taken revenge by ranging under two leaders the flock of the one sheepfold. So deep was the obscurity wherewith miserable intrigues contrived to cover the authority of the legitimate shepherd, that numbers of churches, in all good faith, began to hesitate, and ended at last in preferring the deceptive staff of a hireling. Thicker yet was the darkness to grow, till night should be so dense, that for a moment the conflicting mandates of three Popes would simultaneously spread through the world; whilst the faithful, struck with stupor, would be at an utter loss to discern accurately which was the voice of Christ’s true Vicar. Never had the bride of the Son of God been in a more piteous situation. But Our Lady, to whom the true Pontiff had turned at the first rising of the storm, did not betray the Church‘s confidence. During all those years while the unfathomable justice of the Most High let the powers of hell hold sway, she stood for the defense of holy Church, trampling the head of the old serpent so thoroughly under her victorious foot, that in spite of the terrific confusion he had stirred up, he was unable to sully the faith of the people. Their attachment was steadfast to the unity of the Roman See, whosoever might be, in this uncertainty, its veritable occupant. Thus the West, divided in fact, but in principle ever one and undivided, reunited herself spontaneously as soon as God‘s moment came for the return of light…”
https://stlouiscatholic.wordpress.com/2022/07/02/the-visitation-of-the-blessed-virgin-mary/
“It is granted to few to recognize the true Church amid the darkness of so many schisms and heresies, and to fewer still so to love the truth which they have seen as to fly to its embrace.” -St. Robert Bellarmine