The following quotes are taken from the letters and sermons of Pope Leo I, and deal with the papacy, the Apostolic See of Rome, etc.  The letters and sermons themselves can be found at the New Advent website; I've added a link to the original text for each of the quotes below.  I've used boldface to highlight the sections I think may be of most use to apologists, and bold italics for those that, while being of less use, may nonetheless be of interest...
 
 

LETTER I. TO THE BISHOP OF AQUILEIA.
Let them by their public confession condemn the authors of this presumptuous error and renounce all that the universal Church has repudiated in their doctrine: and let them announce by full and open statements, signed by their own hand, that they embrace and entirely approve of all the synodal decrees which the authority of the Apostolic See has ratified to the rooting out of this heresy.

LETTER VI. TO ANASTASIUS, BISHOP OF THESSALONICA.
Any of the brethren who has been summoned to a synod should attend and not deny himself to the holy congregation: for there especially he should know that what will conduce to the good discipline of the Church must be settled. For all faults will be better avoided if more frequent conferences take place between the priests of the LORD, and intimate association is the greatest help alike to improvement and to brotherly love. There, if any questions arise, under the LORD'S guidance they will be able to be determined, so that no bad feeling remains, and only a firmer love exists among the brethren. But if any more important question spring up, such as cannot be settled there under your presidency, brother, send your report and consult us, so that we may write back under the revelation of the LORD, of whose mercy it is that we can do ought, because He has breathed favourably upon us: that by our decision we may vindicate our right of cognizance in accordance with old-established tradition and the respect that is due to the Apostolic See: for as we wish you to exercise your authority in our stead, so we reserve to ourselves points which cannot be decided on the spot and persons who have made appeal to us.

LETTER IX. TO DIOSCORUS, BISHOP OF ALEXANDRIA.
How much of the divine love we feel for you, beloved, you will be able to estimate from this, that we are anxious to establish your beginnings on a surer basis, lest anything should seem lacking to the perfection of your love, since your meritorious acts of spiritual grace, as we have proved, are already in your favour. Fatherly and brotherly conference, therefore, ought to be most grateful to you, holy brother, and received by you in the same spirit as you know it is offered by us. For you and we ought to be at one in thought and act, so that as we reads, in us also there may be proved to be one heart and one mind. For since the most blessed Peter received the headship of the Apostles from the LORD, and the church of Rome still abides by His institutions, it is wicked to believe that His holy disciple Mark, who was the first to govern the church of Alexandria, formed his decrees on a different line of tradition: seeing that without doubt both disciple and master drew but one Spirit from the same fount of grace, and the ordained could not hand on aught else than what he had received from his ordainer. We do not therefore allow it that we should differ in anything, since we confess ourselves to be of one body and faith, nor that the institutions of the teacher should seem different to those of the taught.

LETTER X. TO THE BISHOPS OF THE PROVINCE OF VIENNE. IN THE MATTER OF HILARY, BISHOP OF ARLES. Our LORD Jesus Christ, Saviour of mankind, instituted the observance of the Divine religion which He wished by the grace of GOD to shed its brightness upon all nations and all peoples in such a way that the Truth, which before was confined to the announcements of the Law and the Prophets, might through the Apostles' trumpet blast go out for the salvation of all men, as it is written: "Their sound has gone out into every land, and their words into the ends of the world." But this mysterious function the LORD wished to be indeed the concern of all the apostles, but in such a way that He has placed the principal charge on the blessed Peter, chief of all the Apostles: and from him as from the Head wishes His gifts to flow to all the body: so that any one who dares to secede from Peter's solid rock may understand that he has no part or lot in the divine mystery. For He wished him who had been received into partnership in His undivided unity to be named what He Himself was, when He said: "Thou art Peter, and upon this rock I will build My Church :" that the building of the eternal temple by the wondrous gift of GOD'S grace might rest on Peter's solid rock: strengthening His Church so surely that neither could human rashness assail it nor the gates of hell prevail against it. But this most holy firmness of the rock, reared, as we have said, by the building hand of GOD, a man must wish to destroy in over-weaning wickedness when he tries to break down its power, by favouring his own desires, and not following what he received from men of old: for he believes himself subject to no law, and held in check by no rules of GOD's ordinances and breaks away, in his eagerness for novelty, from your use and ours, by adopting illegal practices, and letting what he ought to keep fall into abeyance. But with the approval, as we believe, of GOD, and retaining towards you the fulness of our love which the Apostolic See always, as you remember, expends upon you, holy brethren we are striving to correct these things by mature counsel, and to share with you the task of setting your churches in order, not by innovations but by restoration of the old; that we may persevere in the accustomed state which our fathers handed down to us, and please our GOD through the ministry of a good work by removing the scandals of disturbances. And so we would have you recollect, brethren, as we do, that the Apostolic See, such is the reverence in which it is held, has times out of number been referred to and consulted by the priests of your province as well as others, and in the various matters of appeal, as the old usage demanded, it has reversed or confirmed decisions: and in this way "the unity of the spirit in the bond of peace " has been kept, and by the interchange of letters, our honourable proceedings have promoted a lasting affection: for "seeking not our own but the things of Christ," we have been careful not to do despite to the dignity which God has given both to the churches and their priests. But this path which with our fathers has been always so well kept to and wisely maintained, Hilary has quitted, and is likely to disturb the position and agreement of the priests by his novel arrogance: desiring to subject you to his power in such a way as not to suffer himself to be subject to the blessed Apostle Peter, claiming for himself the ordinations of all the churches throughout the provinces of Gaul, and transferring to himself the dignity which is due to metropolitan priests; he diminishes even the reverence that is paid to the blessed Peter himself with his proud words: for not only was the power of loosing and binding given to Peter before the others, but also to Peter more especially was entrusted the care of feeding the sheep. Yet any one who holds that the headship must be denied to Peter, cannot really diminish his dignity: but is puffed up with the breath of his pride, and plunges himself into the lowest depth.
Wherefore, because our desire seems very different to this (for we are anxious that the settled state of all the Churches and the harmony of the priests should be maintained,) exhorting you to unity in the bond of love, we both entreat, and consistently with our affection admonish you, in the interests of your peace and dignity, to keep what has been decreed by us at the inspiration of GOD and the most blessed Apostle Peter, after sifting and testing all the matters at issue, being assured that what we are known to have decided in this way is not so much to our own advantage as to yours. For we are not keeping in our own hands the ordinations of your provinces, as perhaps Hilary, with his usual untruthfulness, may suggest in order to mislead your minds, holy brethren: but in our anxiety we are claiming for you that no further innovations should be allowed, and that for the future no opportunity should be given for the usurper to infringe your privileges. For we acknowledge that it can only redound to our credit, if the diligence of the Apostolic See be kept unimpaired among you, and if in our maintenance of Apostolic discipline we do not allow what belongs to your position to fall to the ground through unscrupulous aggressions.

LETTER XIV. TO ANASTASIUS, BISHOP OF THESSALONICA.
If with true reasoning you perceived all that has been committed to you, brother, by the blessed apostle Peter's authority, and what has also been entrusted to you by our favour, and would weigh it fairly, we should be able greatly to rejoice at your zealous discharge of the responsibility imposed on you.
That we are obliged to speak thus causes us no small grief. For I feel myself in a certain measure drawn into blame, on discovering you to have so immoderately departed from the rules handed down to you. If you were careless of your own reputation, you ought at least to have spared my good name: lest what only your own mind prompted should seem done with our approval. Do but read, brother, our pages with care, and peruse all the letters sent by holders of the Apostolic See to your predecessors, and you will find injunctions either from me or from my predecessors on that in which we learn you have presumed. For there has come to us our brother Atticus, the metropolitan bishop of Old Epirus, with the bishops of his province, and with tearful pleading has complained of the undeserved contumely he has suffered, in the presence of your own deacons who, by giving no contradiction to these woeful complaints, showed that what was impressed upon us did not want for truth.
But if in that which you believed necessary to be discussed and settled with the brethren, their opinion differs from your own wishes, let all be referred to us, with the minutes of your proceedings attested, that all ambiguities may be removed, and what is pleasing to God decided. For to this end we direct all our desires and pains, that what conduces to our harmonious unity and to the protection of discipline may be marred by no dissension and neglected by no slothfulness. Therefore, dearly beloved brother, you and those our brethren who are offended at your extravagant conduct (though the matter of complaint is not the same with all), we exhort and warn not to disturb by any wrangling what has been rightfully ordained and wisely settled. Let none "seek what is his own, but what is another's," as the Apostle says: "Let each one of you please his neighbour for his good unto edifying." For the cementing of our unity cannot be firm unless we be bound by the bond of love into an inseparable solidity: because "as in one body we have many members, but all the members have not the same office; so we being many are one body in Christ, and all of us members one of another." The connexion of the whole body makes all alike healthy, all alike beautiful: and this connexion requires the unanimity indeed of the whole body, but it especially demands harmony among the priests. And though they have a common dignity, yet they have not uniform rank; inasmuch as even among the blessed Apostles, notwithstanding the similarity of their honourable estate, there was st certain distinction of power, and while the election of them all was equal, yet it was given to one to take the lead of the rest. From which model has arisen a distinction between bishops also, and by an important ordinance it has been provided that every one should not claim everything for himself: but that there should be in each province one whose opinion should have the priority among the brethren: and again that certain whose appointment is in the greater cities should undertake a fuller responsibility, through whom the care of the universal Church should converge towards Peter's one seat, and nothing anywhere should be separated from its Head. Let not him then who knows he has been set over certain others take it ill that some one has been set over him, but let him himself render the obedience which he demands of them: and as he does not wish to bear a heavy load of baggage, so let him not dare to place on another's shoulders a weight that is insupportable.

LETTER XVI. TO THE BISHOPS OF SICILY.
BY GOD's precepts and the Apostle's admonitions we are incited to keep a careful watch over the state of all the churches: and, if anywhere ought is found that needs rebuke, to recall men with speedy care either from the stupidity of ignorance or from forwardness and presumption. For inasmuch as we are warned by the LORD'S own command whereby the blessed Apostle Peter had the thrice repeated mystical injunction pressed upon him, that he who loves Christ should feed Christ's sheep, we are compelled by reverence for that see which, by the abundance of the Divine Grace, we hold, to shun the danger of sloth as much as possible: lest the confession of the chief Apostle whereby he testified that he loved GOD be not found in us: because if he (through us) carelessly feed the flock so often commended to him he is proved not to love the chief Shepherd.
You could never have fallen into this fault, if you had taken the whole of your observances from the source whence you derive your consecration to the episcopate; and if the see of the blessed Apostle Peter, which is the mother of your priestly dignity, were the recognized teacher of church-method.
Wherefore we require this first and foremost for the keeping of perfect harmony, that, according to the wholesome rule of the holy Fathers that there should be two meetings of bishops every year, three of you should appear without fail each time, on the 29th of September, to join in the council of the brethren: for thus, by the aid of Gov's grace, we shall the easier guard against the rise of offences and errors in Christ's Church: and this council must always meet and deliberate in the presence of the blessed Apostle Peter, that all his constitutions and canonical decrees may remain inviolate with all the LORD'S priests. These matters, upon which we thought it necessary to instruct you by the inspiration of the LORD, we wish brought to your knowledge by our brothers and fellow-bishops, Bacillus and Paschasinus. May we learn by their report that the institutions of the Apostolic See are reverently observed by you.

LETTER XIX. TO DORUS, BISHOP OF BENEVENTUM.
We grieve that the judgment, which we hoped to entertain of you, has been frustrated by our ascertaining that you have done things which by their blame-worthy novelty infringe the whole system of Church discipline: although you know full well with what care we wish the provisions of the canons to be kept through all the churches of the LORD, and the priests of all the peoples to consider it their especial duty to prevent the violation of the rules of the holy constitutions by any extravagances. We are surprised, therefore, that you who ought to have been a strict observer of the injunctions of the Apostolic See have acted so carelessly, or rather so contumaciously, as to show yourself not a guardian, but a breaker of the laws handed on to you.

LETTER XXIV. TO THEODOSIUS AUGUSTUS II.
What the disturbance was which occurred in the Church of Constantinople, and which could have so moved my brother and fellow-bishop Flavian, that he deprived Eutyches, the presbyter, of communion, I have not yet been able to understand clearly. For although the aforesaid presbyter sent in writing a complaint concerning his trouble to the Apostolic See, yet he only briefly touched on some points, asserting that he kept the constitutions of the Nicene synod and had been vainly blamed for difference of faith.

LETTER XXXIII. To The Synod Of Ephesus
The devout faith of our most clement prince, knowing that it especially concerns his glory to prevent any seed of error from springing up within the catholic Church, has paid such deference to the Divine institutions as to apply to the authority of the Apostolic See for a proper settlement: as if he wished it to be declared by the most blessed Peter himself what was praised in his confession, when the LORD said, "whom do men say that I, the Son of man, am?" and the disciples mentioned various people's opinion: but, when He asked what they themselves believed, the chief of the apostles, embracing the fulness of the Faith in one short sentence, said, "Thou art the Christ, the son of the living God :" that is, Thou who truly art Son of man art also truly Son of the living God: Thou, I say, true in Godhead, true in flesh and one altogether, the properties of the two natures being kept intact.

LETTER XLIII. TO THEODOSIUS AUGUSTUS.
Already and from the beginning, in the synods which have been held, we have received such freedom of speech from the most holy Peter, chief of the Apostles, as to have the power both to maintain the Truth in the cause of peace, and to allow no one to disturb it in its firm position, but at once to repel the mischief.

LETTER XLIV. TO THEODOSIUS AUGUSTUS.
From your clemency's letter, which in your love of the catholic Faith you sent sometime ago to the see of the blessed Apostle Peter, we drew such confidence in your defence of truth and peace that we thought nothing harmful could happen in so plain and well-ordered a matter; especially when those who were sent to the episcopal council, which you ordered to be held at Ephesus, were so fully instructed that, if the bishop of Alexandria had allowed the letters, which they brought either to the holy synod or to Flavian the bishop, to be read in the ears of the bishops, by the declaration of the most pure Faith, which being Divinely inspired we both have received and hold, all noise of disputings would have been so completely hushed that neither ignorance could any longer disport itself, nor jealousy find occasion to do mischief.
...
Which our delegates from the Apostolic See saw to be so blasphemous and opposed to the catholic Faith that no pressure could force them to assent; for in the same synod they stoutly protested, as they ought, that the Apostolic See would never receive what was being passed: since the whole mystery of the Christian Faith is absolutely destroyed (which Heaven forfend in your Grace's reign), unless this abominable wickedness, which exceeds all former blasphemies, be abolished.

LETTER XLV. TO PULCHERIA AUGUSTA.
And they indeed, who were sent, and one of whom, escaping the violence of the bishop of Alexandria who claims everything for himself, faithfully reported to us what took place in the Synod, opposed, as it became them, what I will call the frenzy not the judgment of one man, protesting that those things which were being carried through by violence and fear could not reverse the mysteries of the Church and the Creed itself composed by the Apostles, and that no injuries could sever them from that Faith which they had brought fully set forth and expounded from the See of the blessed Apostle Peter to the holy synod.
And that we may be worthy to obtain this, let your well-tried faith and protection, which has always helped the Church in her labours, deign to advance our petition with our most clement Prince, under a special commission so to act from the blessed Apostle Peter; so that before this civil and destructive war gains strength within the Church, he may grant opportunity of restoring unity by God's aid, knowing that the strength of his empire will be increased by every extension of catholic freedom that his kindly will affects.

LETTER LII.  From Theodoret, Bishop of Cyrus, to Leo.
If Paul, the herald of the Truth, the trumpet of the Holy Ghost, had recourse to the great Peter, in order to obtain a decision from him for those at Antioch who were disputing about living by the Law, much more do we small and humble folk run to the Apostolic See to get healing from you for the sores of the churches. For it is fitting that you should in all things have the pre-eminence, seeing that your See possesses many peculiar privileges. For other cities get a name for size or beauty or population, and some that are devoid of these advantages are compensated by certain spiritual gifts: but your city has the fullest abundance of good things from the Giver of all good. For she is of all cities the greatest and most famous, the mistress of the world and teeming with population. And besides this she has created an empire which is still predominant and has imposed her own name upon her subjects. But her chief decoration is her Faith, to which the Divine Apostle is a sure witness when he exclaims "your faith is proclaimed in all the world;" and if immediately after receiving the seeds of the saving Gospel she bore such a weight of wondrous fruit, what words are sufficient to express the piety which is now found in her? She has, too, the tombs of our common fathers and teachers of the Truth, Peter and Paul, to illumine the souls of the faithful. And this blessed and divine pair arose indeed in the East, and shed its rays in all directions, but voluntarily underwent the sunset of life in the West, from whence now it illumines the whole world. These have rendered your See so glorious: this is the chief of all your goods. And their See is still blest by the light of their God's presence, seeing that therein He has placed your Holiness to shed abroad the rays of the one true Faith.
I however await the verdict of your Apostolic See, and beg and pray your Holiness to succour me when I appeal to your upright and just tribunal, and bid me come to you and show that my teaching follows in the track of the Apostles. For there are writings of mine some 20 years ago, some 18, some 15, and some 12, some again against the Arians and Eunomians, some against the Jews and Greeks some against the Magi in Persia, some also about the universal Providence, Others about the nature of God and about the Divine Incarnation. I have interpreted, through the Divine grace, both the Apostolic writings and the prophetic utterances, and it is easy therefrom to gather whether I have kept unswervingly the standard of the Faith, or have turned aside from its straight path. And I beg you not to spurn my petition, nor to overlook the insults heaped on my poor white hairs.

LETTER LVI. FROM GALLA PLACIDIA AUGUSTA TO  THEODOSIUS.
For no slight harm has arisen from those occurrences, whereby the standard of the catholic Faith so long guarded since the days of our most Divine father Constantine, who was the first in the palace to stand out as a Christian, has been recently disturbed by the assumption of one man, who in the synod held at Ephesus is alleged to have rather stirred up hatred and contention, intimidating by the presence 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 the hands of those who had been deputed to attend the Synod by the most reverend Bishop of Rome, who have been always wont so to attend, most sacred Lord and Son and adored King, in accordance with the provisions of the Nicene Synod. For this cause we pray your clemency to oppose such disturbances with the Truth, and to order the Faith of the catholic religion to be preserved without spot, in order that according to the standard and decision of the Apostolic See, which we likewise revere as pre-eminent, Flavianus may remain altogether uninjured in his priestly office, and the matter be referred to the Synod of the Apostolic See, wherein assuredly he first adorned the primacy, who was deemed worthy to receive the keys of heaven: for it becomes us in all things to maintain the respect due to this great city, which is the mistress of all the earth; and this too we must most carefully provide that what in former times our house guarded seem not in our day to be infringed, and that by the present example schisms be not advanced either between the bishops or the most holy churches.

LETTER LXVIII. FROM THREE GALLIC BISHOPS TO ST. LEO.
Ceretius, Salonius and Veranus to the holy Lord, most blessed father, and pope most worthy of the Apostolic See, Leo.
We acknowledge frankly, most blessed pope, with what singular loving-kindness you have imparted to us the innermost thoughts of your breast, by the efficacy of which you secure the safety of others: and while you extract the old Serpent's infused poison from the hearts of others, standing as it were on the watch-tower of Love, with Apostolic care and watchfulness you cry aloud, lest the enemy come on us unawares and off our guard, lest careless security expose us to attack, O holy Lord, most blessed father and pope, most worthy of the Apostolic See. Moreover we; who specially belong to you, are filled with a great and unspeakable delight, because this special statement of your teaching is so highly regarded wherever the Churches meet together, that the unanimous opinion is expressed that the primacy of the Apostolic See is rightfully there assigned, from whence the oracles of the Apostolic Spirit still receive their interpretations.

LETTER LXIX. TO THEODOSIUS AUGUSTUS.
And when he has realized that that is required and desired from him which shall serve the same good end, let him give his hearty assent to the judgment of the catholics, so that in the presence of all the clergy and the whole people he may without any reservation declare his sincere acknowledgment of the common Faith, to be communicated to the Apostolic See and all the Lord's priests and churches, and thus the world being at peace through the one Faith, we may all be able to say what the angels sang at the Saviour's birth of the Virgin Mary, "Glory in the highest to God and on earth peace to men of good will."

LETTER LXXX. TO ANATOLIUS, BISHOP OF CONSTANTINOPLE.
And that our or rather all Christian people's affection for you may be stirred up in greater measure, we wish this that we have written to you, beloved, to come to all men's knowledge, that they who serve our God may give thanks for the consummation of the peace of the Apostolic See with you. But on other matters and persons you will be more fully instructed, beloved, by the letter you will have received through our delegates.

LETTER LXXXV.  TO ANATOLIUS, BISHOP OF CONSTANTINOPLE.
But concerning those who have sinned more gravely in this matter, and claimed for themselves a higher place in the same unhappy synod, in order to irritate the simple minds of their lowlier brethren by their pernicious arrogance, if they return to their right mind, and ceasing to defend their action, turn themselves to the condemnation of their particular error, if these men give such assurance of penitence as shall seem indisputable, let their case be reserved for the maturer deliberations of the Apostolic See, that when all things have been sifted and weighed, the right conclusion may be arrived at about their real actions. And in the Church over which the Lord has willed you to rule, let none such as we have already written have their names read at the altar until the course of events shows what ought to be determined concerning them.
But concerning the address presented to us by your clergy, beloved, there is no need to put my sentiments into a letter: it is sufficient to entrust all to my delegates, whose words shall carefully instruct you on every point. And so, dearest brother, do your endeavour with these brethren whom we have chosen as suitable agents in so great a matter faithfully and effectually to carry out what is agreeable to the Church of God: especially as the very nature of the case, and the promise of Divine aid incite you, and our most gracious princes show such holy faith, such religious devotion, that we find in them not only the general sympathy of Christians, but even that of the priesthood. Who assuredly in accordance with that piety, whereby they boast themselves to be servants of God, will receive all your suggestions for the benefit of the catholic Faith in a worthy spirit, so that by their aid also the peace of Christendom can be restored and wicked error destroyed. And if on any points more advice is needed, let word be quickly sent to us, that after investigating the nature of the case, we may carefully prescribe the rightful measures.

LETTER XCIII. TO THE SYNOD OF CHALCEDON
I had indeed prayed, dearly beloved, on behalf of my dear colleagues that all the Lord's priests would persist in united devotion to the catholic Faith, and that no one would be misled by favour or fear of secular powers into departure from the way of Truth; but because many things often occur to produce penitence and God's mercy transcends the faults of delinquents, and vengeance is postponed in order that reformation may have place, we must make much of our most merciful prince's piously intentioned Council, in which he has desired your holy brotherhood to assemble for the purpose of destroying the snares of the devil and restoring the peace of the Church, so far respecting the rights and dignity of the most blessed Apostle Peter as to invite us too by letter to vouchsafe our presence at your venerable Synod. That indeed is not permitted either by the needs of the times or by any precedent. Yet in these brethren, that is Paschasinus and Lucentius, bishops, Boniface and Basil, presbyters, who have been deputed by the Apostolic See, let your brotherhood reckon that I am presidings at the Synod; for my presence is not withdrawn from you, who am now represented by my vicars, and have this long time been really with you in the proclaiming of the catholic Faith: so that you who cannot help knowing what we believe in accordance with ancient tradition, cannot doubt what we desire.

LETTER XCVIII.  FROM THE SYNOD OF CHALCEDON TO LEO.
For what is a greater incentive to cheerfulness than the Faith? what better inducement to exultation than the Divine knowledge which the Saviour Himself gave us from above for salvation, saying, "go ye and make disciples of all the nations, baptizing them into the name of the Father, and of the Son, and of the Holy Ghost, teaching them to observe all things that I have enjoined you." And this golden chain leading down from the Author of the command to us, you yourself have stedfastly preserved, being set as the mouthpiece unto all of the blessed Peter, and imparting the blessedness of his Faith unto all. Whence we too, wisely taking you as our guide in all that is good, have shown to the sons of the Church their inheritance of Truth, not giving our instruction each singly and in secret, but making known our confession of the Faith in conceit, with one consent and agreement And we were all delighted, revelling, as at an imperial banquet, in the spiritual food, which Christ supplied to us through your letter: and we seemed to see the Heavenly Bridegroom actually present with us. For if "where two or three are gathered together in His name," He has said that "there He is in the midst of them," must He not have been much more particularly present with 520 priests, who preferred the spread of knowledge concerning Him to their country and their ease? Of whom you were, chief, as the head to the members, showing your goodwill in the person of those who represented you; whilst our religious Emperors presided to the furtherance of due order, inviting us to restore the doctrinal fabric of the Church, even as Zerubbabel invited Joshua to rebuild Jerusalem.
...
Accordingly, we entreat you, honour our decision by your assent, and as we have yielded to the head our agreement on things honourable, so may the head also fulfil for the children what is fitting. For thus will our pious Emperors be treated with due regard, who have ratified your holiness' judgment as law, and the See of Constantinople will receive its recompense for having always displayed such loyalty on matters of religion towards you, and for having so zealously linked itself to you in full agreement. But that you may know that we have done nothing for favour or in hatred, but as being guided by the Divine Will, we have made known to you the whole scope of our proceedings to strengthen our position and to ratify and establish what we have done.

LETTER CIV. (To Marcian Augustus, about the presumption of Anatolius, by the hand of Lucian the bishop and Basil the deacon.)
For although the liberty of the Gospel had to be defended against certain dissentients in the power of the Holy Ghost, and through the instrumentality of the Apostolic See, yet God's grace has shown itself more manifestly (than we could have hoped) by vouchsafing to the world that in the victory of the Truth only the authors of the violation of the Faith should perish and the Church restored to her soundness.
...
Let the city of Constantinople have, as we desire, its high rank, and under the protection of God's right hand, long enjoy your clemency's rule. Yet things secular stand on a different basis from things divine: and there can be no sure building save on that rock which the Lord has laid for a foundation. He that covets what is not his due, loses what is his own. Let it be enough for Anatolius that by the aid of your piety and by my favour and approval he has obtained the bishopric of so great a city.

LETTER CV. TO PULCHERIA AUGUSTA ABOUT THE SELF-SEEKING OF ANATOLIUS.
But the bishops' assents, which are opposed to the regulations of the holy canons composed at Nicaea in conjunction with your faithful Grace, we do not recognize, and by the blessed Apostle Peter's authority we absolutely dis-annul in comprehensive terms, in all ecclesiastical cases obeying those laws which the Holy Ghost set forth by the 318 bishops for the pacific observance of all priests in such sort that even if a much greater number were to pass a different decree to theirs, whatever was opposed to their constitution would have to be held in no respect.

LETTER CVI. TO ANATOLIUS, BISHOP OF CONSTANTINOPLE, IN REBUKE OF HIS SELF-SEEKING.
But blessed be our GOD, whose invincible Truth has shown you free from all taint of heresy in the judgment of the Apostolic See. To whom you will repay due thanks for all these labours, if you keep yourself such a defender of the universal Church as we have proved and do still prove you. For that GOD has dispelled all calumnious fallacies, we attribute to the blessed Peter's wondrous care of us all, for after sanctioning the judgment of his See in defining the Faith, he allowed no sinister imputation to rest on any of you, who have laboured with us for the catholic Faith: because the Holy Spirit adjudged that no one could fail to come out conqueror of those whose Faith had now conquered.

LETTER CXIII. TO JULIAN, BISHOP OF COS.
See then, beloved brother, that you bestow the necessary thought on the cares of the Apostolic See, which by her rights as your mother commends to you, who were nourished at her breast, the defence of the catholic Truth against Nestorians and Eutychians, in order that, supported by the Divine help, you may not cease to watch the interests of the city of Constantinople, lest at any time the storms of error arise within her.

LETTER CXVII. TO JULIAN, BISHOP OF COS.
Wherefore take heed, beloved, that you warn our most gracious prince by frequent reminders that he add his words to ours and order the letter of the Apostolic See to be sent round to the priests of each single province, that hereafter no enemy of the Truth may venture to excuse himself under cover of my silence.

LETTER CXIX. TO MAXIMUS, BISHOP OF ANTIOCH, BY THE HAND OF MARIAN THE PRESBYTER, AND OLYMPIUS THE DEACON.
Of course, if anything is alleged to have been done by those brethren whom I sent in my stead to the holy Synod, beyond that which was germane to the Faith, it shall be of no weight at all: because they were sent by the Apostolic See only for the purpose of extirpating heresy and upholding the catholic Faith. For whatever is laid before bishops for inquiry beyond the particular subjects which come before synodal councils may admit of a certain amount of free discussion, if the holy Fathers have laid down nothing thereon at Nicaea. For anything that is not in agreement with their rules and constitutions can never obtain the assent of the Apostolic See.

LETTER CXX. TO THEODORET, BISHOP OF CYRUS, ON PERSEVERANCE IN THE FAITH.
Wherefore we make our boast in tim LORD, singing with the prophet: "our help is in the name of the LORD, who hath made heaven and earth:" who has suffered us to sustain no harm in the person of our brethren, but has corroborated by the irrevocable assent of the whole brotherhood what He had already laid down through our ministry: to show that, what had been first formulated by the foremost See of Christendom, and then received by the judgment of the whole Christian world, had truly proceeded from Himself: that in this, too, the members may be at one with the Head.
...
For he, who afflicted you with his persecutions, led others wrong by driving them to consent to his wickedness. Yea, even us too, although he had wounded us in each one of the brethren (for they are our members), even us he did not exempt from special vexation in attempting to inflict an injury upon his Head with strange and unheard of and incredible effrontery.
...
But blessed be our GOD, whose invincible Truth has shown you free from all taint of heresy in the judgment of the Apostolic See. To whom you will repay due thanks for all these labours, if you keep yourself such a defender of the universal Church as we have proved and do still prove you. For that GOD has dispelled all calumnious fallacies, we attribute to the blessed Peter's wondrous care of us all, for after sanctioning the judgment of his See in defining the Faith, he allowed no sinister imputation to rest on any of you, who have laboured with us for the catholic Faith: because the Holy Spirit adjudged that no one could fail to come out conqueror of those whose Faith had now conquered.

LETTER CXXIX. TO PROTERIUS, BISHOP OF ALEXANDRIA.
Your letter, beloved, which our brother and fellow-bishop Nestorius duly brought us, has caused me great joy. For it was seemly that such an epistle should be sent by the head of the church of Alexandria to the Apostolic See, as showed that the Egyptians had from the first learnt from the teaching of the most blessed Apostle Peter through his blessed disciple Mark, that which it is agreed the Romans have believed, that beside the LORD Jesus Christ "there is no other name given to men under heaven, in which they must be saved."

LETTER CLVI. To LEO AUGUSTUS.
And lest the pages of this epistle reach too great a length, I have comprised in another letter what is agreeable to the maintenance of the catholic Faith, in order that, though the published statements of the Apostolic See were sufficient, yet these additional statements might also break down the snares of the heretics.

LETTER CLIX. To NICAETAS, BISHOP OF AQUILEIA.
My son Adeodatus, deacon of our See, on returning to us has delivered your request, beloved, to receive from us the authority of the Apostolic See upon matters which seem indeed to be hard to decide, but which we must make provision for with a view to the necessities of the times that the wounds which have been inflicted by the attacks of the enemy may be healed chiefly by the agency of religion.

LETTER CLXII. To Leo Augustus. By the hand of Philoxenus agens in rebus.
And hence by deigning to show a more careful regard for the peace of the universal Church, you manifestly recognize what is the design of the heretics' mighty intrigues that a more careful discussion should take place between the disciples of Eutyches and Dioscorus and the emissary of the Apostolic See, as if nothing had already been defined, and that what with the glad approval of the catholic priests of the whole world was determined at the holy Synod of Chalcedon should be rendered invalid to the detriment also of the most sacred Council of Nicaea.

LETTER CLXVI. To Neo, Bishop of Ravenna.
Consequently the same things, which have come into our mind by the Divine inspiration, have received the assent and confirmation of a large number of the brethren.
 
 

SERMON II. ON HIS BIRTHDAY, II.: DELIVERED ON THE ANNIVERSARY OF HIS CONSECRATION.)
For so far as my own feelings are concerned, I confess that I rejoice most over the devotion of you all; and when I look upon this splendid assemblage of my venerable brother-priests I feel that, where so many saints are gathered, the very angels are amongst us. Nor do I doubt that we are to-day visited by a more abundant outpouring of the Divine Presence, when so many fair tabernacles of GOD, so many excellent members of the Body of Christ are in one place and shine with one light. Nor yet I feel sure, is the fostering condescension and true love of the most blessed Apostle Peter absent from this congregation: he has not deserted your devotion, in whose honour you are met together. And so he too rejoices over your good feeling and welcomes your respect for the LORD'S own institution as shown towards the partners of His honour, commending the well ordered love of the whole Church, which ever finds Peter in Peter's See, and from affection for so great a shepherd grows not lukewarm even over so inferior a successor as myself. In order therefore, dearly beloved, that this loyalty which you unanimously display towards my humbleness may obtain the fruit of its zeal, on bended knee entreat the merciful goodness of our GOD that in our days He will drive out those who assail us, strengthen faith, increase love, increase peace and deign to render me His poor slave, whom to show the riches of His grace He has willed to stand at the helm of the Church, sufficient for so great a work and useful in building you up, and to this end to lengthen our time for service that the years He may grant us may be used to His glory through Christ our LORD.

SERMON III. ON HIS BIRTHDAY, DELIVERED ON THE ANNIVERSARY OF HIS ELEVATION TO THE PONTIFICATE.
Although, therefore, dearly beloved, we be found both weak and slothful in fulfilling the duties of our office, because, whatever devoted and vigorous action we desire to do, we are hindered by the frailty of our very condition; yet having the unceasing propitiation of the Almighty and perpetual Priest, who being like us and yet equal with the Father, brought down His Godhead even to things human, and raised His Manhood even to things Divine, we worthily and piously rejoice over His dispensation, whereby, though He has delegated the care of His sheep to many shepherds, yet He has not Himself abandoned the guardianship of His beloved flock. And from His overruling and eternal protection we have received the support of the Apostles' aid also, which assuredly does not cease from its operation: and the strength of the foundation, on which the whole superstructure of the Church is reared, is not weakened by the weight of the temple that rests upon it. For the solidity of that faith which was praised in the chief of the Apostles is perpetual: and as that remains which Peter believed in Christ, so that remains which Christ instituted in Peter. For when, as has been read in the Gospel lesson, the LORD had asked the disciples whom they believed Him to be amid the various opinions that were held, and the blessed Peter bad replied, saying, "Thou art the Christ, the Son of the living GOD," the LORD says, "Blessed art thou, Simon Bar-Jona, because flesh and flood hath not revealed it to thee, but My Father, which is in heaven. And I say to thee, that thou art Peter, and upon this rock will I build My church, and the gates of Hades shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven. And whatsoever thou shall bind on earth, shall be bound in heaven; and whatsoever thou shall loose on earth, shall be loosed also in heaven."
The dispensation of Truth therefore abides, and the blessed Peter persevering in the strength of the Rock, which he has received, has not abandoned the helm of the Church, which he undertook. For he was ordained before the rest in such a way that from his being called the Rock, from his being pronounced the Foundation, from his being constituted the Doorkeeper of the kingdom of heaven, from his being set as the Umpire to bind and to loose, whose judgments shall retain their validity in heaven, from all these mystical titles we might know the nature of his association with Christ. And still to-day he more fully and effectually performs what is entrusted to him, and carries out every part of his duty and charge in Him and with Him, through Whom he has been glorified. And so if anything is rightly done and rightly decreed by us, if anything is won from the mercy of GOD by our daily supplications, it is of his work and merits whose power lives and whose authority prevails in his See. For this, dearly-beloved, was gained by that confession, which, inspired in the Apostle's heart by GOD the Father, transcended all the uncertainty of human opinions, and was endued with the firmness of a rock, which no assaults could shake. For throughout the Church Peter daily says, "Thou an the Christ, the Son of the living GOD," and every tongue which confesses the LORD, accepts the instruction his voice conveys. This Faith conquers the devil, and breaks the bonds of his prisoners. It uproots us from this earth and plants us in heaven, and the gates of Hades cannot prevail against it. For with such solidity is it endued by GOD that the depravity of heretics cannot mar it nor the unbelief of the heathen overcome it.
And so, dearly beloved, with reasonable obedience we celebrate to-day's festival by such methods, that in my humble person he may be recognized and honoured, in whom abides the care of all the shepherds, together with the charge of the sheep commended to him, and whose dignity is not abated even in so unworthy an heir. And hence the presence of my venerable brothers and fellow-priests, so much desired and valued by me, will be the more sacred and precious, if they will transfer the chief honour of this service in which they have deigned to take part to him whom they know to be not only the patron of this see, but also the primate of all bishops. When therefore we utter our exhortations in your ears, holy brethren, believe that he is speaking whose representative we are: because it is his warning that we give, nothing else but his teaching that we preach, beseeching you to "gird up the loins of your mind," and lead a chaste and sober life in the fear of GOD, and not to let your mind forget his supremacy and consent to the lusts of the flesh. Short and fleeting are the joys of this world's pleasures which endeavour to turn aside from the path of life those who are called to eternity. The faithful and religious spirit, therefore, must desire the things which are heavenly, and being eager for the Divine promises, lift itself to the love of the incorruptible Good and the hope of the true Light. But be sure, dearly-beloved, that your labour, whereby you resist vices and fight against carnal desires, is pleasing and precious in GOD'S sight, and in GOD's mercy will profit not only yourselves but me also, because the zealous pastor makes his boast of the progress of the LORD'S flock. "For ye are my crown and joy," as the Apostle says; if your faith, which from the beginning of the Gospel has been preached in all the world has continued in love and holiness. For though the whole Church, which is in all the world, ought to abound in all virtues, yet you especially, above all people, it becomes to excel in deeds of piety, because founded as you are on the very citadel of the Apostolic Rock, not only has our LORD Jesus Christ redeemed you in common with all men, but the blessed Apostle Peter has instructed you far beyond all men.

SERMON IX. UPON THE COLLECTIONS
...your devotion ought to be foremost in this work, who in your progenitors learnt the Gospel of the Cross of Christ from the very mouth of the most blessed Apostles Peter and Paul.

SERMON LI. A HOMILY DELIVERED ON THE SATURDAY BEFORE THE SECOND SUNDAY IN LENT--ON THE TRANSFIGURATION
To strengthen, therefore, their most wholesome knowledge of this belief, the Lord had asked His disciples, among the various opinions of others, what they themselves believed, or thought about Him: whereat the Apostle Peter, by the revelation of the most High Father passing beyond things corporeal and surmounting things human by the eyes of his mind, saw Him to be Son of the living God, and acknowledged the glory of the Godhead, because he looked not at the substance of His flesh and blood alone; and with this lofty faith Christ was so well pleased that he received the fulness of blessing, and was endued with the holy firmness of the inviolable Rock on which the Church should be built and conquer the gates of hell and the laws of death, so that, in loosing or binding the petitions of any whatsoever, only that should be ratified in heaven which had been settled by the judgment of Peter.

SERMON LVIII. ON THE PASSION.
But, your prayers aiding us, we believe GOD'S Grace will be granted, to sprinkle the barrenness of our heart with the dew of His inspiration: that by the pastor's mouth things may be proclaimed which are useful to the ears of his holy flock.

SERMON LXXIII. (On the Lord's Ascension, I.)
Those days, therefore, dearly-beloved, which intervened between the Lord's Resurrection and Ascension did not pass by in uneventful leisure, but great mysteries were ratified in them, deep truths revealed. In them the fear of awful death was removed, and the immortality not only of the soul but also of the flesh established. In them, through the Lord's breathing upon them, the Holy Ghost is poured upon all the Apostles, and to the blessed Apostle Peter beyond the rest the care of the Lord's flock is entrusted, in addition to the keys of the kingdom.

SERMON LXXIV. (On the Lord's Ascension, II)
For to this devotion the blessed Apostle Peter arouses us, and entreating us with that loving eagerness which he conceived for feeding Christ's sheep by the threefold profession of love for the Lord, says, "dearly-beloved, I beseech you, as strangers and pilgrims, abstain from fleshly lusts which war against the soul."

SERMON LXXXII. ON THE FEAST OF THE APOSTLES PETER AND PAUL (JUNE 29)
But, besides that reverence which to-day's festival has gained from all the world, it is to be honoured with special and peculiar exultation in our city, that there may be a predominance of gladness on the day of their martyrdom in the place where the chief of the Apostles met their glorious end. For these are the men, through whom the light of Christ's gospel shone on thee, O Rome, and through whom thou, who wast the teacher of error, wast made the disciple of Truth. These are thy holy Fathers and true shepherds, who gave thee claims to be numbered among the heavenly kingdoms, and built thee under much better and happier auspices than they, by whose zeal the first foundations of thy walls were laid: and of whom the one that gave thee thy name defiled thee with his brother's blood. These are they who promoted thee to such glory, that being made a holy nation, a chosen people, a priestly and royal state, and the head of the world through the blessed Peter's holy See thou didst attain a wider sway by the worship of God than by earthly government. For although thou wert increased by many victories, and didst extend thy rule on land and sea, yet what thy toils in war subdued is less than what the peace of Christ has conquered.
To this city then, most blessed Apostle Peter, thou dost not fear to come.... And nothing else was demanded of this thy earnest purpose than that thou shouldst bestow the food wherewith thou hadst thyself been enriched, on feeding His sheep whom thou didst love.