Guarding the Faith

Domine victori Theodosio et triumphatori, semper Augusto filio, Galla Placidia, piissima et florens, perpetua Augusta et mater. Dum in ipso ingressu civitatis antiquae hanc curam habuissemus ut cultum beatissimo Petro apostolo redderemus, in ipso adorando altari martyris reverendissimus Leo episcopus, paullum se post orationem retinens, propter catholicam fidem apud nos deflevit, ipsum similiter summum apostolorum, quem nuper adieramus, testem objiciens, episcoporum multitduine circumseptus, quos ex innumerabilibus civitatibus Italiae pro principatu proprii loci seu dignitate collegit; et veribus permiscens lacrymas, ad communionem sui fletus nostros quoque gemitus provocavit. Non enim modicum detrimentum est ex his quae gesta sunt, ut fides, quae tantis temporibus regulariter custodia est a sacratissimo patre nostro Constantino, qui primus imperio splenduit Christianus, nuper turbata sit ad arbitrium unius hominis, qui in synodo Ephesinae civitatis odium et contentiones potius exercuisse narratur, militum praesentia et metu appetens Constantinopolitanae civitatis episcopum Flavianum, eo quod libellum ad apostolicam sedem miserit, et ad omnes episcopos harum partium, per eos qui directi fuerant in concilio a reverandissimo episcopo Romae, qui secundum definitiones Nicaeni concilii consueti sunt interesse, domine sacratissime fili, venerabilis imperator. Hac itaque gratia, tua mansuetudo tantis turbis resistens, veritatem fidei catholicae religionis immaculatam servari praecipiat: ut secundum formam et definitionem apostolicae sedis, quam etiam nos tamquam praecellentem similiter veneramur, in statu sacerdotii illaeso manente per omnia Flaviano, ad concilii et apostolicae sedis judicium transmittatur, in qua primus ille, qui coelestes claves dignus fuit accipere, principatum episcopatus ordinavit; quando scilicet decet nos huic maximae civitati, quae domina omnium est terrarum, in omnibus reverentiam conservare. Diligentius autem etiam in hoc providete, ne quod priscis temporibus nostra generatio custodivit, sub nos imminui videatur, et per praesens exemplum schismata generentur inter episcopos et sanctas Ecclesias. Sanctus Leo Magnus, Epistola LVI, Galla Placidia ad Theodosium

To the Lord Theodosius, victor and conqueror, an ever august son, Galla Placidia, most pious and prosperous, perpetual Augusta and mother.  When having arrived in the ancient city, and having had care to pay our devotion to the most blessed Apostle Peter, at the martyr's very altar, the most reverend Bishop Leo waiting behind a little after the service lamented over the Catholic Faith to us, and bringing forth as witness the chief of the Apostles himself, whom we had just approached, and surrounded by a multitude of bishops whom he had brought together from numerous cities of Italy by the eminence and dignity of his position, mixing tears with his words, he called on us to blend our moans with his weeping. For no slight harm has come from things done by which the Faith, so long guarded since the days of our most holy father Constantine, who was the first in supreme power to shine forth as a Christian, has been recently disturbed by the will of one man, who in the synod held at Ephesus 1 is said to have rather stirred up hate and contention, distressing by the presence and fear of soldiers Flavianus, the bishop of Constantinople, because he had sent an appeal to the Apostolic See, and to all the bishops of these parts by  those who had been sent to the Synod by the most reverend Bishop of Rome, who in accordance to the Canons of the Council of Nicaea have been accustomed attend in such a manner, most sacred Lord and Son and venerable Emperor. Because of this we pray your clemency to resist such disturbances, and to command that the immaculate truth of the Catholic Faith be preserved without spot, that according to the standard and decision of the Apostolic See, which we likewise revere as preeminent, Flavianus may remain uninjured in his priestly office, and the affair be referred to the Synod of the Apostolic See, which he who was worthy to receive the heavenly keys first arranged to have the greatest power; when certainly it becomes us to preserve the honour of this great city, which is the mistress of all the earth. Indeed let us be most diligent to provide for this, lest what in former times our people protected seem by us to be harmed, and that by present example schisms not be caused among bishops and holy churches. Pope Leo the Great, Letter 56, Galla Placidia to Theodosius 1 The Latrocinium of Ephesus