On Pope Leo The Great

AETERNA DEI SAPIENTIA

Encyclical Letter of His Holiness

POPE JOHN XXIII

(November 11, 1961)

Translation provided by NCWC News Service

Write for free publications list to:

NATIONAL CATHOLIC WELFARE CONFERENCE

1312 Massachusetts Avenue, N. W.

Washington 5, D. C.



ENCYCLICAL LETTER

COMMEMORATING THE FIFTEENTH CENTENARY OF

THE DEATH OF SAINT LEO THE GREAT,

SUPREME PONTIFF AND DOCTOR

OF THE CHURCH

TO OUR VENERABLE BRETHREN, THE PATRIARCHS,

PRIMATES, ARCHBISHOPS, BISHOPS AND OTHER
ORDINARIES IN PEACE AND COMMUNION

WITH THE APOSTOLIC SEE

POPE JOHN XXIII

VENERABLE BRETHREN
HEALTH AND APOSTOLIC BENEDICTION

Introduction

The eternal wisdom of God which “reaches from end to end

mightily, and orders all things sweetly
” 1 seems to have im-

pressed His image with singular splendor upon the spirit of the

Supreme Pontiff, St. Leo I.

This “greatest among the great,” 2 as Our predecessor Pius

XII of venerable memory rightly called him, appeared to be

gifted in extraordinary measure with intrepid strength and pa-

ternal goodness. We, called by Divine Providence to- occupy the

Chair of Peter, which St. Leo the Great made so illustrious with

wisdom of government, richness of doctrine, with magnanimity

and with his inexhaustible charity, feel it Our duty, Venerable Bro-

thers, on the occasion of the fifteenth centenary of his blessed

passing, to recall his virtues and immoral merits, certain as We
are that it will contribute notably to the common advantage of
souls and the exaltation of the Catholic religion.

The true greatness of this Pontiff is not chiefly bound to the

fearless act of courage with which he, unarmed and vested solely

1



with the majesty of Supreme Priest, faced the fierce Attila, king

of the Huns, in the year 452, on the banks of the Mincio River and

persuaded him to retreat beyond the Danube. It was undoubtedly

a most noble gesture, especially worthy of the peaceful mission of

the Roman pontificate. But in reality it represents only one episode

and is only one indication of a life that was spent entirely for the

religious and social welfare, not only of Rome and Italy but of the

universal Church.

ST. LEO THE GREAT, PONTIFF, PASTOR AND

DOCTOR OF THE UNIVERSAL CHURCH

The words of Holy Scripture can well be applied to the life

and activity of St. Leo: “The path of the just, as a shining light,

goes forward and increases even to perfect day.” 3 They apply

in considering the three distinct and characteristic aspects of his

personality: as faithful servant of the Apostolic See, as Vicar of

Christ on earth, and as Doctor of the universal Church.

Faithful Servant of the Apostolic See

“Leo, Tuscan by birth, son of Quintianus,” as the Liber

Pontificalis informs us, 4 was born toward the end of the fourth

century. But, since he lived in Rome from his early youth, he

could rightly call Rome his homeland. 5 There, while still a

young man, he was inscribed among the Roman clergy and attain-

ed the diaconate. In the years 430 to 439 he exercised a con-

siderable influence in ecclesiastical affairs, in the service of Pope

Sixtus III. He had friendly relations with St. Prosperus of A-

quitania and with Cassianus, founder of the celebrated Abbey of

St. Victor in Marseilles. From the latter, who urged him to write

“De incarnatione Domini

”

6 against the Nestorians, Leo re-

ceived the truly exceptional, praise for a simple deacon: “Honor

of the Church and of the sacred ministry.” 7

While he was in Gaul, where he was sent by the Pope at the

suggestion of the court of Ravenna to settle the conflict between

the patrician Ezio and the prefect Albino, Sixtus III died. It was

then that the Church of Rome thought that it could not do better
than entrust the power of the Vicar of Christ to the deacon Leo,

who had shown himself to be as sound a theologian as he was a

fine diplomat.

He then received episcopal consecration on September 29, 440,
and his pontificate was one of the longest of the ancient Christian

Church and undoubtedly one of the most glorious. He died in

2



November of 461 and was buried in the porch of the Basilca of St.

Peter. In 688 Pope St. Sergius I had the remains of the holy

pontiff transferred “to the rock of Peter” after the new basilica

had been built, and they now rest beneath the altar dedicated to

him.

Now, wishing simply to indicate the outstanding characteristic

of his life, we can do no less than proclaim that the triumph of

the Church of Christ over its spiritual enemies has rarely been so

glorious as it was during the pontificate of St. Leo the Great.

Truly, in the course of the fifth century he shown in the firma-

ment of Christendom as a shining star. This can in no way be

denied, particularly if one takes into consideration the doctrinal

field of the Catholic faith. His name is, in fact, certainly linked

with those of St. Augustine of Hippo and St. Cyril of Alex-

andria in this field. If St. Augustine, as all know, stood against

the heresy of Pelagius and indicated anew the absolute necessity

of grace to live honestly and achieve eternal salvation, and if St.

Cyril of Alexandria defended against the erroneous affirmations

of Nestorius the divinity of Jesus Christ and the divine maternity

of the Virgin Mary, then for all effects St. Leo is, on his part, heir

of the doctrine of the two distinguished luminaries of the Church

of the East and the West, towers over all his contemporaries in

the clear affirmation of these fundamental truths of the Catholic

faith. And, as St. Augustine is acclaimed in the Church as doctor

of grace, and as St. Cyril is acclaimed as doctor of the Incarnation,

so St. Leo is celebrated above all as the doctor of the unity of the

Church.

Pastor of the Universal Church

It is enough, therefore, to pass rapidly over the prodigious

pastoral and writing activities of St. Leo in the long period of his

pontificate to arrive at the conviction that he was the proclaimer

and defender of the unity of the Church both in the fields of doc-

trine and discipline.

If one passes into the field of liturgy, it is easy to see that

this most pious pontiff promoted the unity of worship, composing

or at least inspiring some of the most elevated prayers, which

are contained in the so-called Sacramentario Leoniano. 8

He furthermore intervened with promptness and authority in

the controversy over the oneness or double nature in Jesus

Christ, achieving the triumph of the true doctrine concerning the

3



Incarnation of the Divine Word of God. By doing this, he immor-

talized his name for posterity.

In this respect one must recall the famous Letter to Flavianus,

Bishop of Constantinople, in which St. Leo outlined with ad-

mirable clarity and propriety the doctrine on the mystery of the

Incarnation of the Son of God, in conformity with the teaching of

the prophets, of the Gospel, of apostolic writings and of the

formula of the Faith. 9

From this letter it seems timely to note the following truly

graphic expressions: “The propriety of both natures remaining

therefore integral, coming together in the single person, human

nothingness was assumed by divine majesty, weakness by power,

mortality by eternity; and in order to satisfy the debt of our con-

dition, the inviolable nature was united to a susceptible nature,

in such a manner that, as was indeed needed for our salvation,

the one and irreplaceable mediator between God and man, the man

Jesus Christ, could indeed die according to
(
one nature, but not

according to the other. Therefore, the Word, though assuming

the complete and perfect nature of true man, was born true God,

complete in His divine properties, complete also in ours.” 10

Nor did he stop at this. Following his letter to Flavianus, in

which he had broadly outlined “all that the Catholic Church be-

lieved and taught universally on the mystery of the Incarnation

of the Lord,” 31 St. Leo condemned the Council of Ephesus of 449.

In this council, in which recourse was had to unlawfulness and

violence, there was an effort to make triumph the erroneous

teaching of Eutychius who, being “very rash and too ignorant,” 12

was obstinate in not wishing to recognize any other than the

one single nature, the divine, in Jesus Christ.

With good reason the Pope called this council “a theft,” 13

because it opposed the clear provisions of the Apostolic See and

dared with every means to “damage the Catholic Faith” 4 and

to strengthen “the heresy which was completely opposed to the

Christian religion.” 15

The name of St. Leo is above all linked with the celebrated

Council of Chalcedon of 451, the convocation of which, though

requested by the Emperor Marcian, was accepted by the Pope

only on condition that it be presided over by his legates. 16 This

council, venerable brothers, constitutes one of the most glorious

pages in the history of the Catholic Church. But we do not con-

sider it necessary to recall it here in detail, since Our predecessor

4



Pius XII dedicated one of his most famous encyclicals, on the 15th

centenary of the event, to this groat assembly, in the course of

which there triumphed with equal splendor the true faith in the

two natures of the Incarnate Word and the primacy of the magis

terium of the Roman Pontiff. 17

The solicitude of St. Leo for the unity and peace of the

Church is evident from the fact that he hesitated to give his ap-

proval to the acts of the council. In reality, this hesitation is not

to be ascribed either to negligence or to any motives of a doctri-

nal character, but—as he himself declared—to his intention of
opposing Canon 28 of the acts of the council. In this Canon the

Fathers of the council, in spite of the protest of the papal legates

and with the obvious wish to gain the favor of the emperor of

Byzantium, gave recognition to the primacy of the See of Con-

stantinople over all the churches of the East.

Ths decision appeared to St. Leo to be an affront to the

privileges of other more ancient and illustrious churches, which

were also recognized by the Fathers of the Council of Nicea. Fur-

thermore, it prejudiced the prestige of the Apostolic See itself.

St. Leo clearly perceived that this danger lay more in the spirit

which dictated it than in the words of Canon 28 itself, as results

clearly from two letters, one of which was addressed to him by the

bishops of the council, 18 and the other sent by him to the emper-

or.

In the latter, refuting the arguments of the Fathers of the

council, he admonished the emperor: “The order of the things of

the world is one thing, and another those things of God; there

can be no stable structure outside of that rock which the Lord

set as a foundation (cf. Matt. 16, 18). One who desires “that is not

his due impairs his own rights.” 19

The sad history of the schism, which subsequently separated

so many illustrious churches of the Christian East from the

Apostolic See—as one may gather from the cited passage—goes
to clearly demonstrate the well-founded fears of St. Leo regard-

ing the future divisions in the heart of Christianity.

Our exposition of the pastoral zeal of St. Leo for the unity

of the Catholic Church would be incomplete if We did not also
recall, even though rapidly, his intervention in the question re-

lating to the feast of Easter, as well as his vigilant concern that

the relations between the Apostolic See and Christian princes be

marked by mutual esteem, trust and cordiality. With the peace

5



of the Church always in view, he frequently exhorted these

princes to cooperate with the episcopate “for full Catholic unity,” 20

to merit from God “in addition to the royal crown, also the palm

of the priesthood.” 21

Doctor of the Church

Besides being a most vigilant pastor of the flock of Christ

and a courageous defender of the orthodox faith, St. Leo is cele-

brated through the centuries as a Doctor of the Church, that is,

as an exponent and most excellent champion of those divine

truths of which every Roman Pontiff is custodian and interpreter.

This is confirmed by the words of Our immortal predecessor,

Benedict XIV, who in the bull “Militantis Ecclesiae,” with which

he proclaimed St. Leo as a Doctor of the Church, formulated this

splendid eulogy: “Through his eminent virtue, through his wis-

dom, through his tireless zeal, he merited from the ancients the

name of Leo the Great. The superiority of his doctrine, both in

illustrating the highest mysteries of our Faith and in defending

them against the rise of errors, as well as in formulating discip-

linary and moral directives, to which may be added a singular

majesty and richness of priestly eloquence, stands out to such a

degree and is distinguished, due to the praise of so many men

and to the enthusiastic exaltations of the councils, the Fathers

and ecclesiastical writers, that a pontiff of such great wisdom is

absolutely not to be placed second in fame and esteem to any of

the holy doctors who flourished in the Church.” 22

His fame as doctor emerges from the homilies and letters

which posterity has preserved for us in considerable numbers.

The collection of homilies embraces different questions, almost

all connected with the cycle of the sacred liturgy. In these

writings he reveals himself not so much as an exegete, dedicated

to the exposition of a particular inspired book, nor as a theologian,

a lover of deep speculations on divine truths, but rather as a

faithful, acute and prolific exponent of Christian mysteries, con-

forming to the interpretations handed down by the councils, the

Fathers and, above all, by the pontiffs who preceded him.

His style is simple and grave, lofty and persuasive, certainly

worthy of being considered a perfect model of classic eloquence.

However, he never sacrificed the accuracy of the truth he wished

to express for elegance of speech. He did not speak or write to

be admired, but to enlighten minds and inflame hearts to perfect

conformity of the practices of life with the truths professed.

6



In the letters, addressed in his capacity as Supreme Pastor to

the bishops, princes, priests, deacons and monks of the universal

Church, St. Leo shows exceptional gifts as a man of government,

that is, an enlightened and supremely practical spirit, a will

ready for action, firm in well matured decisions, a heart open to

paternal understanding and full of that charity that St. Paul in-

dicated to all Christians as “the better way.” 23

How can one not recognize that these sentiments of justice

and of mercy, of strength joined with clemency, were born in his

heart precisely out of that same charity that the Lord required

of Peter before entrusting to him the custody of His lambs and

His sheep? 2 4

He always strove to make of himself a faithful copy of the

Good Shepherd, Jesus Christ, as can be deduced from the follow-

ing passage: “We have on the one hand meekness and clemency,

and on the other strictness and justice. And since all the ways

of the Lord are the result of mercy and truth (—fidelity) (cf.
Ps. 24, 10), we are compelled by the goodness which is proper to

the Holy See to regulate our decisions in such manner that

—

after having pondered the nature of the crimes, the measure of

which varies—we consider that some may be absolved and others
must be rooted out.” 25

Both the homilies and the letters constitute, therefore, a most

eloquent documentation of the thoughts and of the sentiments, of

the words and of the actions of St. Leo, who was always anxious

to insure the good of the Church, in truth, harmony and peace.

THE FIFTEENTH LEONINE CENTENARY AND
THE SECOND VATICAN ECUMENICAL COUNCIL

Venerable Brothers, in the imminence of the Second Vatican

Ecumenical Council, in which the Bishops, gathered about the

Roman Pontiff and in intimate communion with him, will give

to the whole world a more shining spectacle of Catholic unity,

it is all the more instructive and conforming to recall to mind,

even though rapidly, the high idea which St. Leo had of the unity

of the Church. This reminder will be at the same time an act of

homage to the memory of the most wise Pontiff and, in the

coming of the great event, a spiritual food for the souls of the

faithful.

The Unity of the Church in the Thought of St. Leo

St. Leo leaches us above all that the Church is one, because

its Spouse, Jesus Christ, is one: “The Church is the bride, united

7



to Christ, her only Spouse, who admits of no error; so that in all

the world we enjoy a single union, chaste and integral.” 26

The saint believes also that this admirable unity of the

Church began with the birth of the Incarnate Word, as emerges

from these words: “It is the birth of Christ that determines the

origin of the Christian people: the birth of the Head is also the

birth of the body. Even if each one of those called (to the

Faith) enters in his own turn, if all the children of the Church

are distributed in the succession of time, yet the totality of the

faithful, born at the baptismal font, are begotten with Him in

His birth in the same way as they are crucified with Christ in

His Passion, raised up with Him in His Resurrection and placed

at the right hand of the Father in His Ascension.” 27

Mary participated intimately in the mysterious birth of the

“body of the Church,” 28 through her virginity which was made

fruitful by the work of the Holy Spirit. St. Leo exalted Mary as

“Virgin, handmaid and mother of the Lord,” 29 as “Genetrix of

God,” 30 and as perpetual Virgin. 31

The sacrament of Baptism, St. Leo furthermore observes, not

only renders each Christian a member of Christ, but renders him

also a participant in His regality and His spiritual priesthood:

“All those who were regenerated in Christ, are also made king

with the sign of the cross and consecrated priest with the anoint-

ing of the Holy Spirit.” 32 The sacrament of Confirmation, which

he calls “sanctification by chrism,” 33 strengthens this assimilation

to Christ the Head, while in the Eucharist it finds its completion:

“The participation in the Body and Blood of Christ does nothing

less than transform us into that which we consume, and we bear

with us, in flesh and in spirit, Him Himself in whom we died, were
buried and were raised again.” 34

But one must note well that for St. Leo there can be no per-

fect union of the faithful with Christ the Head, nor union among

themselves, as members of the same living and visible organism,

if to the spiritual links of virtue, worship and sacraments there

is not added the external profession of the same faith: “The

integral and true Faith is a great bulwark to which nothing can

be added or taken from by anyone: if the Faith is not single, it

does not exist at all.” 35

It is indispensable, however, to the unity of the Faith that

there be union among the teachers of the divine truths, that is, the

harmony of bishops among themselves in communion and sub-

8



mission to the Roman Pontiff: “The compactness of the whole

body is that which gives origin to its sanctity and beauty, and,

though this compactness requires unanimity, it requires above

all the harmony of its priests. These have priestly dignity in

common, but they do not have the same degree of power; because

also among the apostles there was equality of honor, but differ

ence of power, inasmuch as the grace of election was common to

them all, but the right of pre-eminence over the others was grant-

ed only to one. 36

The Bishop op Rome, Center of Visible Unity

The center and fulcrum of all visible unity of the Catholic

Church, then, is the Bishop of Rome as successor of St. Peter and

Vicar of Jesus Christ. The statements of St. Leo are only the

faithful echo of the Gospel texts and constant Catholic tradition,

as the following passage reveals: “In all the world only Peter is

placed over the evangelization of all people, over all apostles and

over all the Fathers of the Church, so that, although there are

many pastors and priests in the midst of God’s people, all are

governed properly by Peter, as all are governed principally by

Christ. In a great and marvelous way. oh beloved, the Lord

deigned to make this man partaker of His power; and if He

wishes that others also should have something in common with

Him, He grants all to the others always by means of him.” 37

St. Leo believes it is fitting to insist on this truth which is

fundamental to Catholic unity, that is, the divine and indissoluble

bond between the power of Peter and that of the other apostles:

“This power (to bind and to loose: cf. Matt. 14, 91) was certainly

extended also to the other apostles, and it was transmitted to all

the heads of the Church, but it was not without purpose that that

which was to be communicated to all the others was recommend-

ed to one person alone. In fact, this power was entrusted to Peter

particularly, exactly because the figure of Peter stands above all

those who govern the Church.” 38

The Prerogative of Magisterium of St. Peter and His Successors

But the Holy Pontiff does not forget the other essential bond

of the visible unity of the Church, that is, the supreme and

infallible magisterium reserved by the Lord to Peter personally

and to his successors: “The Lord took care of Peter in a special

way; He prayed for the faith of Peter in particular, almost as

though the perseverance of the others would have been better

guaranteed if the soul of their chief would not be overcome. In

9



Peter, therefore, the strength of all is protected, and the assistance

of divine grace follows this order: the strength which was given

to Peter through Christ, is conferred on the other apostles through

Peter.” 39

Whatever St. Leo says with such clarity and insistence about

St. Peter, he says also about himself. He does not do so through

the stimulus of human ambition, but through the deep persuasion

that he is, no less than the Prince of the Apostles, the Vicar of

Jesus Christ Himself, as can be understood from this excerpt of

one of his sermons:

Vast Influence of the Work of St. Leo

“While being filled with gratitude to God for His gift, we

find no reason for pride in solemnly celebrating the anniversary

of our priesthood, for we confess with all sincerity that all the

good which we may have accomplished in our ministry is the

work of Christ and not ours. We can do nothing without Him,
and therefore we glory in Him, from whom derives all the

efficacy of our work.” 40

In saying
1

this, it is far from St. Leo’s mind that St. Peter

ever be a stranger to the government of the Church. On the

contrary, he wants to associate his trust in the constant assistance

of its Divine Founder with his trust in the protection of St. Peter,

whose heir and successor he professes to be, and “in whose stead

all is done.” 41 He attributes to the merits of the Apostle Peter

more than to his own the fruits of his universal ministry. This

is clearly indicated, among other things, in the following ex-

pression: “If, therefore, we accomplish or see any good, if we

obtain anything from the mercy of God with our daily prayers,

it is due to his (Peter’s) works and merits, whose power perdures

in his See and whose authority commands it.” 42

In reality, St. Leo teaches nothing new. Like his predeces-

sors, St. Innocent I 43 and St. Boniface I, 44 and in perfect har-

mony with the well-known Gospel texts upon which he comments

(Matt. 16, 17; Luke 22, 31—32; John 21, 15—17) he is convinced of
having received from Christ Himself the mandate of the supreme

pastoral ministry. He declares: “The care that we must have for

all the Churches has its origin principally in the divine man-

date.” 45

The Spiritual Greatness of Rome

No one should marvel, therefore, if St. Leo associates the

City of Rome with the exaltation of the Prince of the Apostles.

10



This is how he expresses this association in his sermon in honor

of SS. Peter and Paul:

“These, truly, are the heroes, through whose labors, O Rome,

the Gospel of Christ shines for you. . . It is these who raised you

to this glory of being a holy city, a chosen people, a priestly and

a royal city. This is done in such manner that, having become

truly the head of the world in virtue of the Holy See of Blessed

Peter, you might extend your empire more with the divine

religion than it was extended with human domination. Although,

having become powerful through many victories, you did indeed

affirm your right of empire over land and sea, yet that which

the labors of war subjected to you is less than that which Chris-

tian peace gave you.” 46

Reminding his listeners, then, of the splendid testimony

rendered by St. Paul to the faith of the first Christians of Rome,

the great Pontiff urged them with this exhortation to preserve

their Catholic Faith free from any stain of error:

“You, beloved of God and made worthy of the apostolic

approval, to whom the blessed Apostle Paul and doctor of the
gentiles said: “Your faith is proclaimed all over the world”

{Rom. 1,8), preserve, therefore, in yourselves that which you know

he, who exalted you so authoritatively, thought of you. May none

of you make yourselves unworthy of this praise, so that not even

the impiety of Eutychius may contaminate those who, under the

guidance of the Holy Spirit, have never known any heresy for so

many centuries.” 47

The truly outstanding work performed by St. Leo for the

safeguarding of the authority of the Church of Rome was not in

vain. Due to the prestige of his Person, in fact, the “citadel of

the Apostle Peter” was praised and venerated not only by the

Bishops of the West present at the councils in Rome, but also by

more than 500 members of the Oriental Episcopate gathered at

Chalcedon 4a and by the emperors of Constantinople. 49

Even before the famous council, Theodoret, Bishop of Cyrus,

attributed in 449 to the Bishop of Rome and his privileged flock

these high praises:

“Because of the prerogatives which honor your See, yours is

the first place of all. Other cities glory in the fact that they are

either large or have a great number of inhabitants. . . .The Giver

of every good has poured out His bounty on your city in super-

11



abundance, for it is the greatest and most illustrious of all cities,

because it rules the world and is rich in population. . . Further-

more, you possess the tombs of Peter and Paul, common fathers

and masters of truth, who illumine the souls of the faithful.

The two most holy luminaries, indeed, had their origin in the

Orient and cast their rays everywhere, but by their own choice

they suffered death in the West and from there now illuminate

the world. These enobled your See greatly; in this is the culmin-

ation of your goods. But their God even now makes their See

illustrious, while from your sanctity He brings forth in it the rays

of the true Faith.” 50

The illustrious praises which the representatives of the Church

of the Orient attributed to Leo did not diminish with his death.

The Byzantine liturgy, on the feast of February 18 which is dedi-

cated to him, exalts him as “leader of orthodoxy, doctor en-

hanced with piety and majesty, star of the universe, adornment

of the orthodox, harp of the Holy Spirit.” 51

Equally significant are the praises attributed to the great

Pontiff by Menologius Gelasianus: “Our father Leo, admirable

for his many virtues, continence and purity, consecrated Bishop

of the great Rome, did many other things worthy of his virtues:

but his work shone above all in that which concerns the honest

Faith.” 52

Wishes for the Return of the Separated Brothers

We wish to repeat, Venerable Brothers, that the chorus of
praises singing the sanctity of the Supreme Pontiff, St. Leo the

Great was in ancient times agreed upon both in the East and the

West. Oh, may he once more receive the plaudits of all the

representatives of the ecclesiastical learning of the Churches

who are not in communion with Rome.

With the painful differences of opinion about the doctrine and

pastoral action of the immortal Pontiff thus overcome, the

doctrine which they also profess to believe will shine with greater

brilliance: “There is one God and one Mediator between God and

men, Himself man, Christ Jesus.” 53

We, having succeeded St. Leo in the episcopal See of St.

Peter, as We profess with him faith in the divine origin of the
mandate of universal evangelization and salvation entrusted by

Jesus Christ to the Apostles and to their successors, so We
likewise cherish the great desire to see all peoples enter on the

way of truth, charity and peace.

12



And it is precisely for the purpose of rendering the Church

more capable of accomplishing in our times this great! mission

that We decided to convene the Second Vatican Ecumenical
Council. We did so, confident that the impressive gathering of
the Catholic hierarchy would not only strengthen the bonds of

unity in faith, worship and government, which are the preroga

tives of the true Church, n4 but would also attract the attention

of numberless believers in Christ and would invite them to gather

about “the great pastor of the sheep,” 55 who entrusted their

perennial custody to Peter and his successors. r>°

Our warm appeal for unity is intended to be, therefore, the

echo of that which was made many times by St. Leo in the fifth

century, and which was reminiscent of that addressed to the

faithful of all the Churches by St. Ireneus, whom Divine Provi-

dence called from Asia to govern the See of Lyons and to con-

firm it with his martyrdom. After having recognized the unin-

terrupted succession of the Bishops of Rome, heirs of the very

power of the two Princes of the Apostles, 57 he (Ireneus) con-

cluded, exhorting: “Because of its pre-eminent superiority, it is

with this Church that every Church, that is, all the faithful in

the universe, must agree; and it is through communion with it

that all these faithful (or, all the heads of the Churches) have

preserved apostolic tradition.” 58

But Our appeal for unity is intended to be, above all, an echo

of the prayer which Our Saviour addressed to His Divine Father

at the Last Supper: “That all may -be one, even as Thou, Father,

in Me and I in Thee; that they also may be one in Us.” 59 There

is no doubt about the fulfillment of this prayer, just as the

cruel Sacrifice of Golgotha was fulfilled. Did the Lord not say

that His Father always hears Him? 60 We then believe that
the Church for which He prayed and for which He sacrificed

Himself on the cross, and to which He promised His abiding

presence, has always been and remains one, holy, catholic and

apostolic, just as it was instituted.

Unfortunately, as in the past, We must record with sorrow
that also in these times the unity of the Church does not really

correspond to the communion of all believers in one single

profession of faith and in the same practice of worship and of

obedience. However, it is a cause of comfort and of gentle hope

to Us to see those generous and growing efforts done in various

parts of the world for the purpose of reconstructing even the

13



visible unity of all Christians, which responds worthily to the

intentions, commands and wishes of the Divine Saviour.

Realizing that unity, which is the wish of the Holy Spirit in

so many souls of good will, cannot be fully and soundly realized

unless it is in conformity with the prophecy of Jesus Christ that

“there shall be one fold and one shepherd,” 61 We pray Our
Mediator and Advocate with the Father 62 that He may give to

all Christians the grace to recognize the marks of His true

Church that they may become its devout children.

Oh, may the Lord grant that the blessed day of universal

reconciliation may soon dawn, when an immense chorus of

jubilant love will rise! from the one and only family of the re-

deemed and when they, praising the divine mercy, will sing with

the Psalmist: “Behold how good and how pleasant it is for

brethren to dwell together in unity.” 63

The peaceful embrace of the children of the same heavenly

Father, equally coheirs of the same reign of glory, will mark

the celebration of the triumph of the Mystical Body of Christ.

Venerable Brothers, the 15th centenary of the death of St.

Leo the Great finds the Catholic Church in sorrowful conditions

which are similar in part to those which it knew in the fifth

century. How many sufferings truly afflict the Church in these
times and resound in Our paternal heart, as the Divine Redeemer

clearly predicted!

We see that in many regions the “faith of the Gospel” 64

is in danger, and that there are not wanting attempts—which,
thank God, for the most part are doomed to failure—to separate
bishops, priests and faithful from; the center of Catholic unity,

that is, the Roman See.

Therefore, to check these grave dangers, We confidently in-
voke upon the Church militant the patronage of the holy Pontiff

who wrote, suffered and did so much for the cause of Catholic

unity. And to those who patiently cry after truth and justice, We
address the comforting words which St. Leo spoke to the clergy,

to the authorities and to the people of Constantinople: “Per-

severe, therefore, in the spirit of Catholic truth, and through Us

receive the apostolic exhortation: ‘For you have been given the

favor on Christ’s behalf—not only to believe in Him but also to
suffer for Him.’ ” {Phil. 1, 29) 65

14



For all those, finally, who live in the Catholic Faith, We
who, though unworthily, hold the place of the Divine Saviour on

earth, make Ours the prayer which He made for His beloved

disciples and for all those who would have believed in Him:

“Holy Father. . . I pray that they may be perfected in unity.” 00

We, therefore, ask for all the sons of the Church the per-

fection of unity, that perfection which only charity, “the bond

of perfection,” 67 can give. It is from a burning love for God and

the ever ready, cheerful and generous practice of all the works

of mercy toward one’s neighbor that the Church, “temple of the

living God,” is clothed in each and all of its children with

supernatural beauty.

Therefore, with St. Leo We exhort you: “Since, therefore,
all the faithful together and separately constitute the one and

the same temple of God, it is necessary that it be perfect in each

one as it must be perfect in the whole; because, even if the beauty

is not equal in all the members, nor the merits equal in such a

great diversity of parts, the bond of charity produces the com-

munion inj beauty. Those whom a holy love unites, even though
they do not share the same gifts of grace, enjoy their benefits

mutually, however, and that which they love together cannot be

foreign to them, for to find joy in the progress of others increases

their own riches.” 69

At the end of this Apostolic Letter of Ours, may We be per-
mitted to renew the ardent wish that came forth, from the mind

of St. Leo, that is, to see all those redeemed by the Most Precious

Blood of Jesus Christ, reunited in the same Church militant, to

see them resist, united and fearless, the powers of evil which

continue to threaten the Christian faith from so many parts.

Because “the people of God become very powerful when, in

the union of holy obedience, the hearts of all the faithful are in

agreement, when in the camps of the Christian legions the

preparation is the same in all parts and the defenses are the

same everywhere.” 70

The prince of darkness shall not prevail as long as love reigns

in the Church of Christ: “For the works of the demon will be

destroyed with greater power when the hearts of men are burn-
ing with love for God and for neighbor.” 71

May the apostolic benediction which We heartily impart to
all of you, Venerable Brothers, and to the flock entrusted to each

of you, be the comfort of Our hopes and token of divine graces.

15



Given at Rome, at St. Peter’s, November 11, 1961, the fourth

yeaU of Our pontificate.

POPE JOHN XXIII

FOOTNOTES

1 Wisdom

,

8, 1.

2 Cf. Sermon of Oct. 12, 1952, in Discorsi e Radiomesaggi,

XIV, p. 358.

3 Prov., 4, 18.

4 Cf. Ed. Duchesne, I, 238.

5 Cf. Ep. 31, 4, Migne, PL 54, 794.

3 Migne, PL 59, 9-272.

7
jDe Incarn. Domini, contra Nestorium libr. VII, prol. PL

50, 9.

3 Migne, PL 55, 21, 156.

9

Cf. Ibid. 54, 757.

10 “Salva igitur proprietate utriusque naturae et substantiae,

et in unam coeunte personam, suscepta est a maiestate humilitas,

a virtute infirmitas, ab aeternitate mortalitas: et ad resolvendum

conditionis nostrae debitum, natura inviolabilis naturae est unita

passibili: ut, quod nostris remediis congruebat, unus atque idem

mediator Dei et hominum, homo Iesus Christus, et mori posset ex

uno, et mori non posset ex altero. In integra ergo veri hominis

perfectaque natura verus natus est Deus, totus in suis, totus in

nostris.” Ibid. coi. 759.

11 “.
. .quid catholica Ecclesia universaliter de sacramento

Dominicae incarnationis crederet et doceret.” Cf. Ep. 29, ad

Theodosium august. PL 54, 783.

1 2 Cf. Ep. 28, PL 54, 756.

13 Cf. Ep. 95, 2 ad Pulcheriam august. PL 54, 943.

74 Cf. Ibid.

15 cf. Ibid

16 Cf. Ep. 89, 2, ad, Marcianum Imper. PL 54, 931; Ep. 103,

ad Episcopos Galliarum PL 54, 988, 991.

17 Encycl. Letter Sempiternus Rex, Sept. 8, 1951, A. A. 8. a

XXXXIII, vol. 18, p. 625, 644.

18 Cf. C. Kirch, Enchir. fontium hist. eccl. antiquae, Friburgi

in Br. 4 ed. 1923, n. 943.

16



1J) “Alia tamen ratio est rerum saecularium, alia divinarum;

nec praeter illam petram, quam Dominus in fundamento posuit

(Matt. 16, 18), stabilis erit ulla constructio. Propria perdit, qui

indebita concupiscit.” Ep. 104, 3, ad Marcianum Imper. PL 54, 995;

cf. Ep. 106, ad Anatolium, episc. Constant. PL 54, 995.

20 Ep. 114, 3 ad Marcianum Imper. PL 54, 1022.

21 Ibid.

22 Migne, PL 55, 337-340.

23 l Cor. 12, 31.

24 Cf. John 21, 15.17.

2s “Circumstant nos hinc mansuetudo clementiae, hinc cen -

sura iustitiae. Et quia universae viae Domini, misericordia et

veritas, cogimur secundum Sedis Apostolicae pietatem ita nostram

temperare sententiam, ut trutinato pondere delictorum, quorum

utique non una mensura est, quaedam credamus utcumque

toleranda, quaedam vero penitus amputanda.” Ep. 12, 5, ad Epis-

copos africanos
,
PL 54, 652.

26 “Illa est enim virgo Ecclesia, sponsa unius viri Christi,

quae nullo patitur errore vitiari; ut per totum mundum una nobis

sit unius castae communionis integritas.” Ep. 80, 1, ad Anatolium,

episc. Constant. PL 54, 913.

27 “Generatio enim Christi origo est populi Christiani, et

natalis Capitis natalis est corporis. Habeant licet singuli quique

vocatorum ordinem suum, et omnes Ecclesiae filii temporum sint

successione distincti, universa tamen summa fidelium, fonte orta

baptismatis, sicut cum Christo in passione crucifixi, in resurrec-

tione resuscitati, in ascensione ad' dexteram Patris collacati, ita

cum ipso sunt in hac nativitate congeniti.” Serm. 26, 2, in Nativ.

Domini, PL 54, 213.

28 Coi. 1, 18.

29 Ep, 165, 2, ad Leonem, imper. PL 54, 1157.

so Cf. Ibid .

31 Serm. 22, 2, in Nativ. Domini, PL 54, 195.
32 “Omnes enim in Christo regeneratos, crucis signum efficit

reges, Sancti vero Spiritus unctio consecrat sacerdotes.” Serm. 4,

1, in Nativ. Domini, PL 54, 149; cf Serm. 64, 6, de Passion Domi-

ni, PL 54, 357; Ep 69, 4, PL 54, 870.

38 Serm. 66, 2, de Passione Domini, PL 54, 365-366.

34 “Non enim aliud agit participatio Corporis et Sanguinis

Christi, quam ut in id quod sumimus transeamus; et in quo com-

mortui, et consepulti, et conresuscitati sumus, ipsum per omnia

17



et spiritu et carne gestemus.” Serm. 64, 7, de Passione Domini,

PL 54, 357.

35

“Magnum praesidium est fides integra, fides vera, in qua

nec augeri ab ullo quidquam, nec minui potest: quia nisi una est,

fides non est.” Serm. 24, 6, in Nativ. Domini, PL 54, 207.

36 “Connexio totius corporis unam sanitatem, unam pulchri-

tudinem facit; et haec connexio totius quidem corporis unanimi-

tatem requirit, sed praecipue exigit concordiam sacerdotum. Qui-

bus cum dignitas sit communis, non est tamen ordo generalis:

quoniam et inter beatissimos apostolos in similitudine honoris

fuit discretio potestatis; et cum omnium par esset electio, uni

tamen datum est ut caeteris praeemineret.” Ep. 14, 11, ad Anas-

tasium, episc. Thessal. PL 54, 676.

37 “De toto mundo unus Petrus eligitur, qui et universarum

gentium vocationi, et omnibus apostolis, cunctisque Ecclesiasae

Patribus praeponatur: ut quamvis in populo Dei multi sacerdotes

sint multique pastores, omnes tamen proprie regat Petris, quos

principaliter regit et Christus. Magnum et mirabile, dilectissimi,
huic viro consortium potentiae suae tribuit divina dignatio; et si

quid cum eo commune caeteris voluit esse principibus, numquam

nisi per ipsum dedit quid quid alis non negavit.” Serm. 4, 2, de

natali ipsius, PL 54, 149-150.

38 ‘‘Transivit quidem etiam in alios apostolos ius potestatis

istius (hoc est, ligandi atque solvendi) et ad omnes Ecclesiae

principes decreti huius constitutio commeavit; sed non frustra uni

commendatur, quod omnibus intimetur. Petro enim ideo hoc

singulariter creditur, quia cunctis Ecclesiae rectoribus Petri forma

praeponitur.” Ibid. coi. 151; cf. Serm. 83, 2, in natali s. Petri Apost.

PL 54, 430.

39 “Specialis a Domino Petri cura suscipitur, et pro fide Petri

proprie supplicatur, tamquam aliorum status certior sit futurus,

si mens principis victa non fuerit. In Petro ergo omnium fortitudo

munitur, et divinae gratiae ita ordinatur auxilium, ut firmitas

quae per Christum Petro tribuitur, per Petrum apostolis confera-

tur.” Serm. 4, 3, PL 54, 151-152; cf. Serm. 83, 2, PL 54, 451.

40 “Non est itaque nobis praesumptuosa festivitas qua sus-

cepti sacerdotii diem divini muneris memores honoramus; quan-

doquidem pie et veraciter confitemur, quod opus ministerii nostri

in omnibus quae recte agimus, Christus exsequitur; et non in nobis,

qui sine illo nihil possumus, sed! in ipso, qui possibilitas nostra

est, gloriamur.” Serm. 5, 4, de natali ipsius, PL 54, 154.

41 Cf. Serm. 3, 4, de nat. ipsius, PL 54, 147.

18



42 “Si quid itaque a nobis recte agitur, recteque discernitur,

si quid a misericordia Dei quotidianis supplicationibus obtinetur,

illius est operum atque meritorum, eius in sede sua vivit potestas

et excellit auctoritas.” Serm. 3, 3, de nat. ipsius , PL 54, 146; cf.

Serm. 83, 3, in nat. S. Petri Apost. PL 54, 402.

43 Ep. 30, ad Concil. Milev. PL 20, 590.
44 Ep. 13, ad Rufum episc. Thessaliae

,

11 mart. 422, in C.

Silva-Tarouca S. I. Epistolarum Romanorum Pontificum collect.

Thessal. Romae 1937, p. 27.

45 “Curam quam universis Ecclesiis principaliter ex divina

institutione debemus.” Ep. 14, 1, ad Anastasium, episcop. Thessal.

PL 54, 668.

46 “Isti enim sunt viri per quos tibi Evangelium Christi,

Roma, resplenduit. . . Isti sunt qui te ad hanc gloriam provexer-

unt, ut gens sancta, populus electus, civitas sacerdotalis et regia,

per sacram beati Petri sedem caput orbis effecta, latius praesi-

deres religone divina quam dominatione terrena. Quamvis enim

multis aucta victoriis ius imperii tui terra marique protuleris,

minus tamen est quod tibi bellicus labor subdidit, quam quod pax

Christiana subiecit.” Serm. 82, 1, in nat. Apost. Petri et Pauli, PL

54, 422-423.

47 “Vos ergo, dilecti Deo et apostolico testimonio comprobati,

quibus beatus apostolus Paulus, doctor gentium, dicit: Quoniam

fides vestra annunatiatur in universo mundo custodite in vobis

quod tantum praedicatorem agnoscitis sensisse de vobis. Nemo

vestrum efficiatur huius laudis alienus, ut quos per tot saecula

docente Spiritu Sancto haeresis nulla violavit, ne Eutychianae

quidem impietatis possint maculare contagia.” Serm. 86, 3, tract

contra haer. Eutychis. PL 54, 467.
48 Mansi, Concil. ampliss. collect. VI, p. 913.

49 Ep. 100, 3, Marciani imper ad Leonem, episc. Romae, PL

54, 972; Ep. 77, 1, Pulcheriae aug. ad Leonem, episc. Romae, PL 54,

907.

50 Ep. 52, 1, Theodoreti episc. ad Leonem, episc. Romae, PL

54, 847.

51 Mena,ia tou holou eniautou III, Roma 1896 p. 612.

52 Migne, PG 117, 319.

53 l Tim. 2, 5.

54 Cf. Cone. Vat. I, Sess. Ill, cap. 3 de fide.

55 Heb. 13, 20.

56 Cf. John 21, 15-17.

19



57 Cf. Advers. haeres. 1, III, c. 2, n. 2, PG 7, 848.

58 ibid.

59 John 17, 21.

eo Cf. Io. 11, 42.

61 Ibid. 10, 16.

62 Cf. 1 Tim. 2, 5; I John 2, 1.

63 ps . 132, 1.

64 Cf. Phil 1, 27.

65 “State igitur in spiritu catholicae veritatis, et apostolicam

cohortationem ministerio nostri oris accipite.” Ep. 50, 2 ad Con-

stantinopoliianos, PL 54, 843.

66 Cf. John 17:11, 20, 23.

67 Coi. 3, 14.

68 Cf. 2 Cor. 6, 16.

69 “Cum igitur et omnes simul et singuli quique fidelium

unum idemque Dei templum sint, sicut perfectum hoc in universis,

ita perfectum devet esse in singulis: quia etsi non eadem est

membrorum omnium pulchritudo, nec in tanta varietate partium

meritorum potest esse parilitas, communionem tamen obtinet

decoris connexio charitatis. In sancto enim amore consortes,

etiamsi non iisdem utuntur gratiae beneficiis, gaudent tamen in-

vicem bonis suis, et non potest ab eis extraneum esse quod dili-

gunt, quia incremento ditescunt proprio, qui profectu laetantur

alieno.” Serm. 48, 1, de Quadrag. PL 54, 298-299.

70 “Tunc fit potentissimus Dei populus, quando in unitatem

sanctae oboedientiae omnium fidelium corda conveniunt, et in

castris militiae Christianae similis ex omni parte praeparatio, et

eadem est ubique munto.” Ep. 22, 2, PL 54, 441-442.

71 “Quia tunc opera diaboli potentius destruuntur, cum ad Dei

proximique dilectionem hominum corda revocantur.” Ep. 95, 2, ad

Pulcheriam august, PL 54, 943.

20