“And what need is there of many words, when it is possible to refute falsehood in few? We provide that those who year by year come up for holy baptism should carefully learn the faith set forth at Nicaea by the holy and blessed Fathers; and initiating them as we have been bidden, we baptize them in the name of the Father and of the Son and of the Holy Ghost, pronouncing each name singly” (Letters 145 [A.D. 444]).

“We are guarding the dogmatic teaching of the Apostles intact even to the present time. Handing this teaching down to us are not only the Apostles and the prophets, but also those whose writings interpret their books, Ignatius, Eustathius, Athanasius, Basil, Gregory, John, and the other lights of the ecumene, and before these the holy Fathers gathered in Nicaea, whose confession of faith we guard inviolate as a paternal inheritance”
-LETTER OF THEODORET, BISHOP OF CYR, TO FLORENTIUS 89
(Written 449 A.D.)

“But Apollinaris, who values drivel more than truth, and who sets his homely prattle before the pious dogmas, says God the Word put on (1) flesh and used it rather like a veil (2); and that, having no need of a soul (3), He takes the place of a soul (4) in the body. But, my dear, someone may say to Apollinaris that God the Word had no need of a body either, for He had no lack at all. He was able even to carry out our salvation by a simple command; but He wanted also to have some properly arranged communion with us. To that end He assumed sinful nature (5) and justified that nature by His own deeds. He set it free from the bitter tyrants, Sin and Devil and Death, and deemed it worthy of heavenly thrones, and through that which He assumed He gave to all the race a share in liberty.”
-THE THEOLOGY OF THE TRINITY AND THE DIVINE
INCARNATION 18: 1-5 [ante A. D. 430]

“[Tatian] also put together the Gospel called the Diatessaron, pruning away the genealogies and the other [parts] which show that the Lord was born of the seed of David according to the flesh. And it found use not only among the members of his own sect but even with those who are followers of the Apostolic teachings, and who, unable to perceive the villainy of the compilation, in their simplicity use it as a concise Bible (1). And I myself have discovered more than two hundred books of this kind held in honor in our own churches; and I have gathered them all together and sequestered them and have introduced in their place the Gospels of the four Evangelists.”
-COMPENDIUM OF HERETICS’ FABLES 1:20 (ca. A. D. 453)

“Thus completing the sacrament of Baptism (2), we receive the hope of resurrection and expect the resurrection of bodies. The term itself makes this clear. For ἀνάστασις (resurrection) means standing up alive again (3). It is the body that is corrupted and dissolved and changed into a mound of earth.”
-COMPENDIUM OF HERETICS’ FABLES 5:19 (ca. A. D. 453)

“Those whom He predestined, those also did He call; and those whom He called, those also did He justify; and those whom He justified, those also did He glorify (1). Those whose resolve He foreknew, He predestined from the beginning. Predestining them, He did also call them. Calling them, He justified them by Baptism; and justifying them, He glorified them, calling them sons and bestowing on them the grace of the Holy Spirit. But no one would say that His foreknowledge is the cause of this: for His foreknowledge does not accomplish such things as these. Rather, God, since He is God, does see from afar those things that are going to be. . .”
-INTERPRETATION OF THE FOURTEEN EPISTLES OF PAUL [On Rom. 8:30]

“The God of the universe, since He is God, sees all things from afar. Assuredly this imposes no necessity on anyone of practicing virtue, nor on anyone of doing evil. For if a man be compelled to either course, it is not right that he be either praised and crowned, or condemned to punishment. If God is just, as just He be, He encourages to those things that are good, and dissuades from the contrary; and He praises those who do good, and punishes those who voluntarily embrace evil.”
–INTERPRETATION OF THE FOURTEEN EPISTLES OF PAUL [On Rom. 8:30]

“For by grace you have been saved through faith (2).” The grace of God deems us worthy of these good things. And all we bring to it is our faith. But even in this the divine grace has become our co-worker. For [Paul] adds, ‘And this is not of yourselves, but it is a gift of God; not of works, lest anyone should boast (3).” It is not of our own accord that we have believed, but we have come to belief after having been called; and when we had come to believe, He did not require of us purity of life, but approving mere faith, He bestowed on us forgiveness of sins.”
-INTERPRETATION OF THE FOURTEEN EPISTLES OF PAUL [On Eph. 2:8]

“[Paul] yokes together bishops and deacons, making no mention of presbyters (4); certainly it was not possible that many bishops should be shepherds in one city, so it is clear that he calls the presbyters bishops. Indeed, in the same Epistle he called the Blessed Epaphroditus their apostle: ‘Your apostle,’ he says, ‘and the co-worker of my necessity.’ Clearly, therefore, Epaphroditus, since Paul gives him the title of apostle, has been entrusted with the episcopal office.”
-INTERPRETATION OF THE FOURTEEN EPISTLES OF PAUL [On Phil. 1:1]

“At that time they called the same persons presbyters and bishops; and those we now call bishops they designated apostles. In the course of time, however, they abandoned the name of apostle to those who truly were Apostles; and the title of bishop they accorded to those who had of old been called apostles. Thus Epaphroditus was apostle of the Philippians: ‘Your apostle,’ he says, ‘and the co-worker of my necessity.’ Thus in Crete Titus and in Asia Timothy were apostles. Thus too the apostles and the
presbyters wrote from Jerusalem to those in Antioch.”
INTERPRETATION OF THE FOURTEEN EPISTLES OF PAUL [On 1 Tim. 3:1]

“I therefore beseech your holiness to persuade the most holy and blessed bishop (Pope Leo) to use his Apostolic power, and to order me to hasten to your Council. For that most holy throne (Rome) has the sovereignty over the churches throughout the universe on many grounds.” (Theodoret, Tom. iv. Epist. cxvi. Renato, p. 1197).

“It pertains to you (Pope Leo) to hold the primacy in all things, for your throne is adorned with many prerogatives.” (Theodoret Ibid, Epist. Leoni)

“If Paul, the herald of the truth, the trumpet of the Holy Spirit, hastened to the great Peter, to convey from him the solution to those in Antioch, who were at issue about living under the law, how much more do we, poor and humble, run to the Apostolic Throne (Rome) to receive from you (Pope Leo) healing for wounds of the the Churches. For it pertains to you to have primacy in all things; for your throne is adorned with many prerogatives.” (Theodoret Ibid, Epistle Leoni)

“For that all holy throne has the office of heading the Churches of the whole world, for many reasons; and, above all others, because it has remained free of the communion of heretical taint, and no one holding heterodox sentiments ever sat in it, but it has preserved the Apostolic grace unsullied.” (Theodoret, Epist Renato)

“Hasten to your Apostolic See in order to receive from you a cure for the wounds of the Church. For every reason it is fitting for you to hold the first place, inasmuch as your see is adorned with many priviledges. I have been condemned without trial. But I await the sentence of your Apostolic See. I beseech and implore Your Holiness to succor me in my appeal to your fair and righteous tribunal. Bid me hasten to you and prove to you that my teaching follows in the footsteps of the Apostles.” (Theodoret to Pope Leo, Ep. 113).