Mystici Corporis Christi: Pope Pius XII's Encyclical On The Doctrine Of The Mystical Body Of Christ

Pope Pius XII in 1924. His papacy was from 1939-1958.

Pope Pius XII's encyclical, Mystici Corporis Christi was issued on the Feast of the Holy Apostles Peter and Paul, June 29, 1943. It is a document that explains the doctrine of the Mystical Body of Christ, which is the Church. It is an invitation to all who are drawn to it by the Holy Spirit to study it; to receive the truths contained within it; and to act upon this knowledge and understanding with the performance of good works. Pope Pius XII deemed it fitting to develop and explain this doctrine with the hope that the entire flock of Christ would, "...[D]raw certain lessons that will make a deeper study of this mystery bear yet richer fruits of perfection and holiness." (11)

If you are new to Church doctrine, you might be asking yourself, what exactly is a doctrine. Doctrine is defined by the Oxford English Dictionary as, "a set of beliefs or principles held and taught by a religious, political, or other group." With specific reference to the Catholic Church, here is what the Catechism of The Catholic Church states about doctrine and the constitutive element of charity:

The whole concern of doctrine and its teaching must be directed to the love that never ends. Whether something is proposed for belief, for hope or for action, the love of our Lord must always be made accessible, so that anyone can see that all the works of perfect Christian virtue spring from love and have no other objective than to arrive at love. (25)

Thirty six pages printed, there is much one could include in writing about this encyclical, but for the sake of brevity, today's post focuses on some of the fundamental aspects of this doctrine: the origins of this doctrine; certain aspects of the Mystical Body; why the body in fact is mystical; errors that have arisen from an incorrect understanding of this doctrine; and the participation of each member to strengthen and build up the Mystical Body of Christ.

Pope Pius XII explanation on the origin of this doctrine begins at paragraph twelve, with the fall of Adam and the gift of Christ. God created Adam in such an exalted state that he was to hand on to his posterity the heavenly life of divine grace. After Adam's fall, the entire human race was "infected with a hereditary stain," in which it lost its participation in the divine nature. God's love for the world brought with it the gift of His only begotten Son. Christ's crucifixion not only appeased the justice of the Father, but had obtained for all mankind an ineffable flow of graces. It was possible for Christ to impart these graces to mankind directly; but He willed to do so only through a visible Church, that all might cooperate with Him in dispensing the graces of redemption. It is significant to note that the establishment of the Mystical Body was willed by Christ, so that the sacred work of redemption would endure and continue throughout the centuries, in part due to the direct participation of His Body.

Pope Pius XII also noted that the establishment of the Mystical Body by Christ, had been reinforced by the teaching of Sacred Scriptures and the Holy Fathers. He cited Saint Paul's letter to the the Colossians, "Christ is the Head of the Body of the Church," (14) as well as Pope Leo XIII's encyclical, Satis Cognitum, who asserted that the "Church is visible because she is a body." (14) 

Further on in the encyclical, Pope Pius XII identified who is included in the Body. The Body consists of the clergy and the laity: those who are of Holy Orders; cloistered in monasteries living a contemplative life; others who are active and living in the world in their apostolates; those in the state of matrimony, single laity and members of lay Catholic groups. He elaborated further on this when he stated:

...only those are to be included as members of the Church who have been baptized and profess the true faith, and who have not been so unfortunate as to separate themselves from the unity of the Body, or been excluded by legitimate authority for grave faults committed. "For in one spirit" says the Apostle, "were we all baptized into one Body, whether Jews or Gentiles, whether bond or free." As therefore in the true Christian community there is only one Body, one Spirit, one Lord, and one Baptism, so there can be only one faith. And therefore, if a man refuse to hear the Church, let him be considered - so the Lord commands - as a heathen and a publican. It follows that those who are divided in faith or government cannot be living in the unity of such a Body, nor can they be living the life of its one Divine Spirit. (22)

Pope Pius XII clarified that the Mystical Body of Christ is made up of holy individuals, saints and sinners as well. He noted that not every sin, grave as it may be, will sever man from the Mystical Body of Christ. He stated that if members of the Body have lost charity and divine grace through sin, they may not be deprived of all life if they hold fast to faith and Christian hope; spurred by the promptings of the Holy Spirit to prayer and penance for their sins. Such is not the case with much more serious matters such as schism, heresy or apostasy. 

Christ has provided for His Mystical Body by endowing it with the Sacraments. In so doing, as Pope Pius XII noted, He provided it with an uninterrupted series of graces to sustain it from birth to death, including generous provisions for the social needs of the Church. In particular, Pope Pius XII spotlighted the great importance of the correct religious education of children, in which he stated that without the "Mystical Body would be in grave danger." (20)

Continuing with his explanation of the Body, Pope Pius XII stated that, "Because Christ the Head holds such an eminent position, one must not think that he does not require the help of the Body." (44) Important to note that what ever need our Divine Redeemer has of us, ultimately we must remember His words, "I am the vine; you are the branches. If you remain in me and I in you, you will bear much fruit; apart from me you can do nothing." (John 5:15) We, the Body, must always be cognizant of the fact that all advancement of "...[T]his Mystical Body towards its perfection derives from Christ the Head." (44) 

Pope Pius XII stated very clearly, "Christ has need of His members." (44) As to the specifics why Christ needs His members, he elaborated on this point when he stated that Jesus is represented by the Supreme Pontiff, who in turn must call upon others to share in the solicitude of souls, lest he become overwhelmed by the demands of his pastoral office. Pope Pius XII also stressed that our Saviour does not rule the Church directly in a visible manner, but instead He wills to be helped by the members of his Body, carrying out the work of redemption. The reason for this; Christ willed to be helped by his Body for the "greater glory of His spotless Spouse." (44) Pope Pius XII continued with this explanation when he stated that when Christ died on the Cross, He left the Church with the immense treasury of Redemption. Come time to distribute the graces, not only does Christ share this work of sanctification with His Church, but He wills that in some way it would be due to her action. Pope Pius XII referred to this as a deep mystery: 

...that the salvation of many depends on the prayers and voluntary penances which the members of the Mystical Body of Jesus Christ offer for this intention and on the cooperation of pastors of souls and of the faithful, especially of fathers and mothers of families, a cooperation which they must offer to our Divine Savior as though they were His associates. (44)

As to why the Body of Christ should be called Mystical, Pope Pius XII began his explanation at paragraph sixty. So there may be no misunderstanding of what mystical means, the Oxford English Dictionary defines it as "having a spiritual significance that goes beyond human understanding." Father John Hardon's Modern Catholic Dictionary,  definition of the Church's mystical component is as follows, "The Church is called Mystical because she is a mystery, which God revealed to be true but whose inner essence must be accepted on faith and without full comprehension by the mind." Here is the introduction to the mystical aspect of the Body from Pope Pius XII:

And now, Venerable Brethren, We come to that part of Our explanation in which We desire to make clear why the Body of Christ, which is the Church, should be called mystical. This name, which is used by many early writers, has the sanction of numerous Pontifical documents. There are several reasons why it should be used; for by it we may distinguish the Body of the Church, which is a Society whose Head and Ruler is Christ, from His physical Body, which, born of the Virgin Mother of God, now sits at the right hand of the Father and is hidden under the Eucharistic veils; and, that which is of greater importance in view of modern errors, this name enables us to distinguish it from any other body, whether in the physical or the moral order. (60)

To further clarify the Mystical aspect of the Body, Pope Pius XII compared the Mystical Body to that of a natural body. He stated that in a natural body, "...the principle of unity unites the parts in such a manner that each lacks in its own individual subsistence; on the contrary, in the Mystical Body the mutual union, though intrinsic, links the members by a bond which leaves to each the complete enjoyment of his own personality." (61) He explained further that the different members of the physical body are destined to the good of the whole alone; while the Mystical Body with its many moral associations are directed to the advancement of all and each individual member. He then pointed out the fact that Jesus established the Body and enriched it with the Holy Spirit; for it exists "...[F]or the good of the faithful and for the glory of God and of Jesus Christ whom He sent." (61)

A further comparison was made between a mystical and moral body. Pope Pius XII noted the difference between the two is not slight, but rather considerable and very important. Here is what he stated:

In the moral body the principle of union is nothing else than the common end, and the common cooperation of all under the authority of society for the attainment of that end; whereas in the Mystical Body of which We are speaking, this collaboration is supplemented by another internal principle, which exists effectively in the whole and in each of its parts, and whose excellence is such that of itself it is vastly superior to whatever bonds of union may be found in a physical or moral body. (62)

Pope Pius XII continued to explain that the Church, as a perfect society, is not merely made up of moral and juridical elements and principles; it is far superior to all other human societies. It is superior to all human societies because it surpasses them as grace surpasses nature, as things immortal are above all that can perish. The Church is not found within a natural order, rather the juridical principles upon which the Church rests and is established derive from the divine constitution given to it by Christ. Our Redeemer continues to penetrate and fill every part of the Church's being; He is active within until the end of time as the source of every grace, gift and miraculous power.

With respect to the many errors that have arisen from an incorrect understanding of some aspects of this doctrine, Pope Pius XII included many paragraphs (85-90). Of particular note is the error of "quietism." The error of quietism is one that assumes that the whole spiritual life of Christians and their progress is exclusively the result of the actions of the Holy Spirit; while neglecting the collaboration that is due of each member of the Body. No one should deny the inspirations and role of the Holy Spirit in the Church with each member, but at the same, each member should as Pope Pius XII stated, "...[A]dvance eagerly in grace and virtue, that they should strive earnestly to reach the heights of Christian perfection and at the same time to the best of their power should stimulate others to attain the same goal..." (87) He explained that the Holy Spirit will not effect all this unless members of the Body contribute daily with their share of zealous activity. 

Another error that Pope Pius XII warned about is the assertion by some who have given little importance to the frequent confession of venial sins. He explained that although venial sins are forgiven and expiated at daily Mass, the sacrament of reconciliation provides for more rapid progress in virtue. Here is what he stated on the encouragement of frequent confession:

...We will that the pious practice of frequent confession, which was introduced into the Church by the inspiration of the Holy spirit, should be earnestly advocated. By it genuine self-knowledge is increased, Christian humility grows, bad habits are corrected, spiritual neglect and tepidity are resisted, the conscience is purified, the will strengthened, a salutary self-control is attained, and grace is increased in virtue of the Sacrament itself. Let those, therefore, among the younger clergy who make light of or lessen esteem for frequent confession realize that what they are doing is alien to the Spirit of Christ and disastrous for the Mystical Body of our Savior... (88)

Participation of each member to strengthen and build up the The Mystical Body of Christ, is specifically mentioned and encouraged at paragraph ninety eight. Pope Pius XII began this paragraph with the love that Christ has for His Body; a love that is to be reciprocated by its members. Of particular note, Pope Pius XII mentioned the Italian Catholic lay group, Catholic Action, which spotlighted the importance of the laity's role in the Body. Pope Pius XII pointed out that as Jesus laboured unceasingly to establish and strengthen the Church, that all of its members should endeavour to do likewise. This encyclical was issued during the middle of World War II, which Pope Pius XII referred to as the "present circumstances," the significance of which he spotlighted by stressing how important it was for everyone to realize the urgent necessity of their energetic zeal in working for the Body. 

Further aspects of each member's participation in the strengthening and building up of the Body, is included at paragraph one hundred and six. Pope Pius XII stated that we should pray for the Lord to send labourers into His harvest and that our daily prayer should be united in praying to the Lord for all members of the Mystical Body of Christ. He elaborated as to how we can effectively work for the Body; drawing God's graces upon it in the process:

For although our Savior's cruel passion and death merited for His Church an infinite treasure of graces, God's inscrutable providence has decreed that these graces should not be granted to us all at once; but their greater or lesser abundance will depend in no small part on our own good works, which draw down on the souls of men a rain of heavenly gifts freely bestowed by God. These heavenly gifts will surely flow more abundantly if we not only pray fervently to God, especially by participating every day if possible in the Eucharistic Sacrifice; if we not only try to relieve the distress of the needy and of the sick by works of Christian charity, but if we also set our hearts on the good things of eternity rather than on the passing things of this world; if we restrain this mortal body by voluntary mortification, denying it what is forbidden, and by forcing it to do what is hard and distasteful; and finally, if we humbly accept as from God's hands the burdens and sorrows of this present life. Thus, according to the Apostle, "we shall fill up those things that are wanting of the sufferings of Christ in our flesh for His Body, which is the Church." (106)

In publishing this post today, it is my hope that an increasing number of Catholics will read and study this encyclical and; thus, come to a better understanding of the Body, that is the Church. May it encourage many to strive with a firm resolution to sincerely work to strengthen and build up the Mystical Body of Christ. In so doing, may each one of us be cognizant of each member's role and dignity, to which we have been called by our Head, Jesus Christ our Saviour and Redeemer. 


May Our Lady Queen of Peace intercede for us.