II. The Mystical Body in the 1930s-1950s

Let me begin with representative theologians from the 1930s through the 1950s, in addition to the encyclical Mystici Corporis. Emile Mersch, the first of these theologians, remains fairly well known for his book The Whole Christ: The Historical Development of the Doctrine of the Mystical Body in Scripture and Tradition, first published in 1933. Mersch argues that in the thirteenth-century for theologians such as Aquinas ‘the doctrine of the Mystical Body no longer occupies its position of prominence’.^{Footnote 8} This is so, Mersch says, due to Aristotelian philosophy, Roman juridical thought, and the difficulty of defining ‘the Mystical Body in the precise formulas required for syllogistic argumentation’.^{Footnote 9} In making this claim, Mersch is representative of those who were reacting against the regnant neo-scholastic theology of the day.

Mersch recognizes, however, that in the thirteenth century, the Mystical Body was hardly ignored. He especially values Aquinas's insistence that Christ, as Head, communicates his own personal grace to the members of his Body. Aquinas thereby presents ‘the whole life of grace in the members of the Mystical Body as a prolongation of that supreme grace whereby the Head of the body is constituted the very Son of God and the Holy of holies’ (although Aquinas differentiates between Christ's grace of union and his habitual grace).^{Footnote 10} Given this view of the Mystical Body, there is a direct connection between Christ's Cross and the life of the Church. For Aquinas, all Christ's actions, ‘especially his passion and death, His resurrection and ascension, affect us directly’.^{Footnote 11}

Aquinas's argument that Christ and his members act as ‘one mystic person’ especially impresses Mersch. Mersch aptly describes Aquinas as teaching that ‘when Christ suffers, all humanity is redeeming itself in Him’.^{Footnote 12} The suffering of the Head is never separated from that of the Body. According to Mersch, then, the redemptive Cross is at the center of the Mystical Body, since Christ's sacrifice is not the mere action of an isolated individual. Put simply, the Body of Christ shares in the redemption won by Christ because the Body of Christ shares in the Head's sacrifice on Calvary.

In his 1935 The Mystical Body of Christ, Fulton Sheen—then a professor of theology at Catholic University of America, trained in the Thomism of the University of Louvain, and soon to be famous as a groundbreaking evangelist—approaches the Mystical Body from a multitude of angles. These include the ‘soul’ of the Church (the Holy Spirit, which launches Sheen into a variety of subtopics, such as the Church's catholicity), the relationship between the Church's nature as Christ's Mystical Body and the fact that the Church is marked by the scandal of sin, the infallibility and authority of the Church, Mary and the Mystical Body, the Eucharist as constitutive of the unity of the Mystical Body, and Catholic social action (social justice), among others.^{Footnote 13} I will focus solely on the role that the Cross plays in Sheen's understanding of the Mystical Body.

Sheen begins by emphasizing the fact that Christ is not simply a man who died (and rose again) two millennia ago. Rather, Christ's humanity was, in his earthly life, the instrument of his divinity; and this did not come to an end. It is the case today, in fact, that Christ's ‘life, death, Resurrection, and Ascension are the instruments of Divinity for our sanctification, our life, our resurrection, our ascension’.^{Footnote 14} Christ acted in the world as priest, prophet, and king. Today, through his Mystical Body the Church, he continues to act in the world as priest, prophet, and king. Moreover, Christ is so intimately bound with the members of his Mystical Body that if they are persecuted he is persecuted, and when they are cared for, he is cared for. Sheen adds that, as can be recognized in the sacraments, ‘The Church, … the totus Christus (the whole Christ), as St Augustine calls it, is continuing the Incarnation by prolonging the theandric actions of the historical Christ’.^{Footnote 15}

One way that the Church does this is through the Eucharist, which Sheen identifies as ‘the sacrifice of the Mystical Body’.^{Footnote 16} As Sheen explains, ‘On the Cross the “Historical” Christ offered Himself, in the Mass the “Mystical” Christ which is Christ and us, are associated in the offering’.^{Footnote 17} It is through the Church as the Body of Christ that we are able to share in the salvific sacrifice offered by Christ on the Cross. The glorious saving power of the Cross, its status as the perfect offering, now involves us as we are truly united to and offered in Christ's sacrifice through the liturgical act. Christ, through his Mystical Body, incorporates us and joins us fully into his one saving Cross.

Sheen emphasizes, therefore, that the Body of Christ is not simply the communion of believers incorporated into Christ by the bond of love. At least, this Body cannot be understood unless love is viewed in light of the Cross. To share in the Eucharistic communion, we must possess a ‘spirit of sacrifice’.^{Footnote 18} We must be configured to Christ's dying, through our own dying to our self-centered selves. The love that unites the Body of Christ is the ‘Incarnate Love [who] emptied Himself of His Life on the Cross’.^{Footnote 19} In short, the Church as the Mystical Body consists in those who love as Christ loved us on the Cross. The blessed in the state of glory will be those who, as Sheen poetically puts it, ‘filled up once again with love the Divine Chalice, which God Himself drained in making and redeeming us’.^{Footnote 20}

The Thomist theologian Charles Journet's multi-volume L’Église du Verbe incarné belongs among the classic works of Catholic theology. In a section written in the late 1940s, he devotes a few hundred pages to the theme of the Body of Christ, which he treats after discussing the uncreated soul of the Church (the Holy Spirit) and the created soul of the Church (organizing principles such as the sacramental characters and jurisdictional structures). The Body of Christ is ‘the extension of Christ in space and time’.^{Footnote 21} Christ is the Head of the Body. The Pauline ‘body of Christ’ includes what Journet distinguishes as soul and body. Journet reflects upon the relationship between Christ's flesh and his Body the Church. Discussing the constitutive elements of the Church as the Body of Christ, Journet approaches the topic from the perspective of the Church's efficient, formal, and final causes. Efficiently, the motion of Christ and the Spirit brings about the Body of Christ, extending and prolonging Christ in time and space. Formally, Christ's capital grace—a ‘fully Christic grace’,^{Footnote 22} sacramental and cultic—is the inherent cause of the Body of Christ. The final cause is not only Christic grace and the Holy Spirit, but the whole Trinity transforming humans and leading them to glory.

Journet holds that these three causes are aligned with the essential dimensions of the Church as the Body of Christ: the cultic dimension, the prophetic dimension, and the dimension of holiness. According to the Letter to the Hebrews, Christ the priest accomplishes our salvation by entering with his blood into the heavenly sanctuary. As Journet says, Christ ‘gave to his death on the Cross the character of a definitive sacrificial offering’.^{Footnote 23} This offering cannot be repeated, but it can be participated in, and this was Christ's plan, through baptism, the Eucharist, and the other sacraments. The importance of sacramental character is found here, because the three sacramental ‘characters’—imprinted by baptism, confirmation, and holy orders—participate in and derive from Christ's priesthood, his Cross. Journet states with respect to holy orders, ‘The hierarchical character of order communicates the power of rendering present and efficacious the redemptive sacrifice’ of Christ, which takes place in the Eucharist.^{Footnote 24} Holy orders ensures that the redemptive power of the Cross is able to course through the Body of Christ. For its part, the baptismal character enables the believer to receive the sacrament of the Eucharist, and not only to receive it passively, by to ‘co-offer the sacrifice of the Mass’.^{Footnote 25}

Journet speaks of ‘three concentric circles’ that are present in the cultic dimension of the Body of Christ,^{Footnote 26} which is the dimension that he discusses first (without denigrating the prophetic dimension and the dimension of sanctity). The first circle is the very heart of the Body of Christ: Christ's own redemptive sacrifice on the Cross. Flowing out from Christ's Cross are the sacraments and the public prayers and liturgical offices. For my purposes, the key point is the centrality of the Cross for the Body of Christ. The Church, in its cultic dimension, has been ‘consecrated in order to continue validly in the world the cult inaugurated by Christ the priest’.^{Footnote 27} Through the unbloody rite of the Last Supper, the Church is able to make present to all generations Christ's unique sacrifice on the Cross—in accordance with numerous biblical passages that affirm the Church's cultic, sacramental, and liturgical work.

Journet notes that the 1947 encyclical Mediator Dei highlights the Church's priestly extension of the power of Christ's priestly sacrifice on the Cross. After providing a lengthy quotation from Mediator Dei, Journet points out that the reason the Church is able to exercise the same priestly cult across the ages is because of ‘Christ's presence in all the acts of the cult of his Church’.^{Footnote 28} The blood of Christ, shed on the Cross, remains always at the center of the Body of Christ—without overshadowing the fact that the risen, glorious Christ who will come again is always proclaimed as well by this same cult. Eschatological remembrance and promise go together.

Journet goes on to take up a variety of topics, including the ‘coextensivity’ of the soul and Body of the Church—which means that where charity is (and thus where the indwelling Spirit is), there is the Church. Journet pays special attention to the role of the Spirit. He explores the relation of the ‘visible supernatural society’ of the Church to ‘the nations, visible temporal societies’.^{Footnote 29} He investigates the Catholic understanding of the Church's visibility in comparison to Calvin's understanding of this same topic. He treats the hierarchical and non-hierarchical acts of the Church. But, while attending to all these themes (and many others), he keeps in mind the Cross's centrality for the Body of Christ, since ‘the Passion of Christ is the meritorious and redemptive cause of the salvation of all humans without exception’, even if this cause is applied differently in accordance with whether people live before or after Christ.^{Footnote 30} Christ acts in his Body in diverse ways, and the Church as Christ's Body shares in Christ's prophetic and royal authority as well as his priesthood. But the aspect of his priesthood—his Cross—is never marginal for understanding the Church as the Body of Christ.^{Footnote 31}

The Austrian Augustinian priest Pius Parsch was a leader in the liturgical movement. In the early 1950s he prepared a collection of sermons for all Sundays and feast-days of the year, to which he added, as an Appendix, ten sermons on the Mystical Body. The first nine sermons do not refer much, if at all, to the Cross. Instead, these sermons build upon Pope Pius XII's 1943 encyclical Mystici Corporis by focusing on divine grace. The Church mediates to us the grace of the Holy Spirit, ‘which is an inchoation of glory’ or deification.^{Footnote 32} Parsch grounds his account of the Mystical Body in the doctrine of grace. Christ is the source of all grace; Christ the Head fills his Body with the grace of his Spirit. Christ is the very center of everything. He founded the Church, his Mystical Body, by his preaching and teaching, his redemptive death, and his pouring out the Spirit at Pentecost. Christ dwells in his Body and continues to sustain and build it up.

Parsch grants that the Church has contained not only saints but also many wicked persons (including wicked clergy) and scandals, and he grants that the Church's exercise of political rule and of judicial authority has hardly been spotless, to say the least. But to know the Church properly, one must know it as Christ's Body. Insofar as they are truly members of the Church, possessing the grace of Christ, the Church's many members are one because they share in the one life of grace that comes from the Head. The ‘soul’ of the Body is the Spirit, which Christ breathed into his Church at Pentecost. Believers are temples of the Spirit, and all the various functions of the Body come from grace of the Spirit, mediated by the sacraments. As Parsch says, ‘members of Christ's Mystical Body live with Christ's life. And this life is sanctifying grace’.^{Footnote 33}

Parsch develops this point in various directions, including by highlighting fraternal charity, the communion of saints, the visibility of the Church as the Mystical Body, the relationship of believers to non-Christians, the relation of non-Catholics to the Mystical Body, the status of Catholics in a state of sin, the ‘sacramental character’ given by Baptism and Confirmation, the nature of the priesthood, the characteristics and power of faith, the observance of the commandments, the diversity of vocations and states of life, Catholic marriage and family life, and so on. But in his final sermon, on ‘The Mystical Body and the Season of Lent’, he makes a strong, though brief, connection to the Cross. Although the Church is holy, the Church's members on earth are sinners, with the exception of Mary. To have and dwell in a Body with sinful members, says Parsch, belongs to Christ's emptying of himself in absolute humility, and it entails that the Mystical Body needs purification. Parsch draws a powerful conclusion from this fact. He states, ‘The Mystical Body of Christ, in passing through this world, must follow the same path as that which was traversed by Christ in his physical body during his earthly life’.^{Footnote 34} This path includes the Cross: ‘The body and the members must suffer with their head, must die and rise and attain to glory’.^{Footnote 35} Lent requires a tangible participation of the Mystical Body in the Cross of Christ through prayer, fasting, and almsgiving or works of mercy.^{Footnote 36}

Lastly in this section, let me briefly mention some aspects of Pius XII's Mystici Corporis. The completion of the Mystical Body, Mystici Corporis teaches, took place on the Cross. The blood and water from the side of Christ established the Church, which, as the New Eve, came forth from the side of the New Adam. Through the blood of Christ, the human race was reconciled to God, the gifts of the new covenant were poured out, and the Church fully brought to be. On the Cross, Christ is fully the Head of the Church, conquering original sin and uniting human beings to himself. Through Christ's blood, the Temple veil was rent and the Church received the fullness of the Holy Spirit. On the Cross, Christ gave to his Body the divine gifts that ensure that the Church can always teach, govern, and sanctify its members.

As biblical evidence for the centrality of the Cross in constituting the Church, Mystici Corporis appeals to Ephesians 2:13-16, where Paul teaches that the Gentile believers ‘have been brought near in the blood of Christ’ because Christ has united Jews and Gentiles by reconciling ‘us both to God in one body through the cross’. It is on this basis that the encyclical gives a place to the outpouring of the Spirit at Pentecost.^{Footnote 37} Christ reigns ‘directly and personally’, as well as through the Church's apostolic hierarchy.^{Footnote 38} Christ gives particular graces to each member of his Body. In this way, Christ configures the Body to himself, so that it is truly ‘his body, the fullness of him who fills all in all’ (Eph 1:23) and so that the members ‘grow up in every way into him who is the head,… from whom the whole body, joined and knit together by every joint with which it is supplied, when each part is working properly, makes bodily growth and upbuilds itself in love’ (Eph 4:15-16).

As Head of his Body, Mystici Corporis emphasizes, Christ is not merely the leader of a community of people. Rather, ‘Christ is the Divine Savior of this Body’.^{Footnote 39} This explains why the Cross must be central to the proper understanding of the Mystical Body. Christ, in and through his saving Cross, continually acts for the salvation of his Body. The Mystical Body is comprised of the Savior and those whom he saves. He not only reconciles the members of his Body to God, but he also gives them supernatural and deifying life. He does the latter through the outpouring of his Spirit, who ‘is the principle of every supernatural act in all parts of the Body’.^{Footnote 40}

Furthermore, the Eucharistic sacrifice unites the Body in the saving self-offering of the Head. In the Eucharistic sacrifice, the priest acts in persona Christi on behalf of the whole Mystical Body. In union with the priest's prayers, the faithful—and thus the entire Mystical Body—offers the saving sacrifice of Christ to the Father. In the Eucharistic sacrifice (which is the Church's offering of the one sacrifice of the Cross), Christ can be said to offer ‘to the heavenly Father not only Himself as Head of the Church, but in Himself His mystical members also, since He holds them all, even those who are weak and ailing, in His most loving Heart’.^{Footnote 41}

The final paragraphs of Mystici Corporis highlight the love of Christ. Christ loves the whole human race, each and every human being. The encyclical reminds us that Christ's Cross was for the salvation of the whole world, with the goal of uniting the whole world into the Body of Christ. We must therefore love all human beings as at least potential members of the Body and as ‘our brothers in Christ according to the flesh’.^{Footnote 42} The Mystical Body involves no cheap grace, no fellowship or communion rooted simply in good-will rather than in the Cross of Christ. Christ freely endured the Cross out of love for his Body, and so ‘it was only at the price of His Blood that He purchased the Church’.^{Footnote 43} The members of the Body are members only insofar as they ‘follow gladly in the bloodstained footsteps’ of Christ the Head. By sharing in his Cross, the members of his Body will share (and even now share) in his Resurrection.^{Footnote 44}

III. Thomistic Interpretations of the Mystical Body from the 1960s to the 2000s: Hamer, Le Guillou, Sabra, Torrell, and Rikhof

In his 1962 The Church Is a Communion, Jerome Hamer—an influential voice in the development and promotion of Catholic communion ecclesiology—devoted a chapter to exploring the Mystical Body from the perspective of Thomas Aquinas. Hamer notes that M. D. Koster, critically reflecting upon Augustine and Aquinas, argued in 1940 that their ecclesiology was primarily spiritual: they interpreted even the expression ‘body of Christ’ non-corporeally, as the invisible Church across the ages. Other students of Aquinas offered a similar criticism that ‘St Thomas may have shown the influx of the life of Christ into the Church, but he did not give sufficient place to the corporeity of the “mystical body”’.^{Footnote 45} In response, Hamer directs attention to the instrumentality of Christ's humanity and, more specifically, to the human actions of Christ as causing grace in us. Since Christ is the incarnate Son, he is our Head not only with respect to our souls but also with respect to our bodies. Although the Church has existed from Abel onward, it has never existed as a merely spiritual communion: it has always been united by corporeal sacraments. The inclusion of the angels does not make the Mystical Body non-corporeal, given that Christ is Head of the angels in a different sense than he is Head of human beings.

Hamer lays particular emphasis upon the Eucharist. For Aquinas, the ‘res sacramenti’ of the Eucharist is the Mystical Body in its unity (united by love).^{Footnote 46} The conclusion that Hamer draws is that, for Aquinas, Christ's real body ‘is the proper cause of the mystical body as a conjoint instrument [of the Son]’.^{Footnote 47}

Although Hamer's book focuses upon ‘communion’ as the basis for ecclesiology, he draws his definition of the Church from the theology of the Mystical Body. He defines the Church as follows: ‘The Church is the mystical body of Christ, that is to say a communion which is at once inward and external, the life of union with Christ, and established (caused) by the economy of Christ's mediation’.^{Footnote 48} Hamer examines the way in which communion with Christ is interior and spiritual and also involves outward forms, including the episcopacy and papacy, as well as the generative causes of communion (the saving mysteries of Christ's life). He thinks of the Mystical Body primarily in terms of interpersonal communion, which governs his ecclesiology. As he says, ‘Because of its union with Christ, the Church is a mystery of interdependence, a network of relationships between persons…. We must restore to the term “communion”, with all its aura of tradition and meaning, its rightful importance’.^{Footnote 49}

I should add that Hamer's investigation of the term ‘communion’ leads him deep into the causes of this communion, including the Father's sending of the Son into the world as Messianic priest, prophet, and king.^{Footnote 50} Hamer emphasizes the Eucharist and the common priesthood of the faithful, whose task is to offer worship or spiritual sacrifice to God.^{Footnote 51} In reflecting upon the New Testament meaning of ‘koinonia’ (communion), he recognizes that believers ‘participate in the blood of Christ, in his body, in the Son himself, in his sufferings and in the Spirit’.^{Footnote 52} In the patristic Church, ‘communion’ often referred to churches being in eucharistic communion with each other. Hamer's focus is on communion in the sense of unity of faith, sacraments, and fellowship, inclusive of the apostolic (hierarchical) structure of the Church, and brought about by the Holy Spirit and charity, as well as by Christ's diverse modes of presence in the Church (especially in the Eucharist). While not absent, the Cross is not central to Hamer's ecclesiology, either with respect to the Mystical Body or with respect to the Church as communion.

M.-J. Le Guillou's Thomistic study Christ and Church: A Theology of the Mystery, originally published in 1963, treats the Mystical Body at length. Drawing upon a wide array of Aquinas's texts, Le Guillou begins by emphasizing, ‘Absolutely unique, and immediately caused by the assumptive divine action alone, the gratia capitis of Christ enabled Him to unite all men to Himself through the agency of his humanity’.^{Footnote 53} It is because of Christ's grace of Headship that he can, on the Cross, merit for all human beings. Likewise, as members of his Body through his grace, we can ‘merit in Him and through Him’.^{Footnote 54} All Christ's acts, not solely his Passion, merit salvation for us. Explicating Aquinas, Le Guillou understands the Incarnation as, from the outset, the redemptive Incarnation. Christ's perfect personal grace is always, at the same time, his grace of Headship. We, Christ's members, are included in the plan of the Incarnation.

Le Guillou provides a lengthy quotation from Summa theologiae III, q. 8, a. 1, where Aquinas treats Christ as Head of his Body the Church. He notes that Aquinas draws upon a variety of important biblical texts, many of which can be found also in Aquinas's commentary on Romans 8:29. Among the notable biblical texts are John 1:14 and 1:16, where Jesus is presented as full of grace and as the source of grace to all who receive grace. Romans 8:29 teaches that the purpose of this grace is to configure us to Christ's image, so that we become brothers of Christ and heirs with Christ of the inheritance of God the Father (deification). Indebted to Yves Congar, Le Guillou observes that, according to both Scripture and Aquinas, ‘through His Body, Christ is the principle of a new creation’.^{Footnote 55} Specifically, the Body of Christ is constituted by the sending of the Spirit; where the Spirit dwells, there is the ‘Church of the baptized, the prophetic, priestly, and royal people, who participate in the anointing of Christ, the prophet, priest, and king’.^{Footnote 56} In sum, the Body of Christ is the Catholic Church, enlivened by the Spirit and ‘measured by the mediation of Christ as Head’.^{Footnote 57}

Le Guillou directs attention to the centrally of the Eucharist. He argues that the Eucharist constitutes the Church, as ‘a commemorative participation in the act of Christ saving the world and offering to His Father the worship which is due Him’.^{Footnote 58} According to Aquinas, every grace proceeds from the Eucharist; and so Le Guillou associates the Eucharist and the Spirit as constituting the Church as the Body of Christ. Faith and baptism, along with the bond of charity, also play a central role, of course, as do the Church's hierarchical offices. Christ's Body is a visible Body. Through the Eucharist, the members of the Body are united to the salvific ‘offering made by Christ upon the Cross’; and the effect of sharing in the Eucharist is charity (manifested supremely by Christ in his Passion), building up the Church in unity.^{Footnote 59}

For Le Guillou (interpreting Aquinas), the Mystical Body is a particularly exciting way to understand the Church because the Church is all about the pouring out of the grace of the Holy Spirit by Christ, ‘the Head of His Body’.^{Footnote 60} As Christ's Body, the Church mediates his grace to the world. The Body of Christ also mediates the teachings and sacraments of Christ the Head. After briefly discussing Aquinas on the priesthood (including the episcopacy), Le Guillou emphasizes the spiritual sacrifice offered by the Body of Christ, which grows ‘in the likeness of its glorious Head’.^{Footnote 61} The ‘Mystery of Christ’ is center of Aquinas's ecclesiology: the Body of Christ manifests Christ. The Cross is part of this mystery, and Le Guillou mentions the Cross in connection with the Eucharist, but the Cross is not a central element of Le Guillou's portrayal of the Mystical Body according to Aquinas.

In his 1987 Thomas Aquinas’ Vision of the Church, George Sabra draws attention to a wide range of literature treating Aquinas's understanding of the Mystical Body, including various studies published in the 1930s and 1940s.^{Footnote 62} Sabra highlights the Eucharistic dimension of Aquinas's understanding of the Mystical Body,^{Footnote 63} as well as Aquinas's emphasis on Christ's grace of headship as the source (in the Spirit) of the members’ diverse gifts and offices. Sabra recognizes, ‘The church as corpus (Christi) mysticum is a central and characteristic designation in the ecclesiological thought of Thomas Aquinas’.^{Footnote 64} Yet, Sabra does not discuss the significance of the Cross in Aquinas's doctrine of the Mystical Body.^{Footnote 65}

In Saint Thomas Aquinas: Spiritual Master, first published in 1996, Jean-Pierre Torrell reflects at some length on what he calls ‘the Christological coloration of grace’.^{Footnote 66} Torrell observes that Christ, as the Head of his Body, is the source of grace to all those who are joined to him as members of his Body. Christ causes grace in us in a deeply personal way, as our Head rather than as a mere instrumental cause. Torrell emphasizes, therefore that in Aquinas's mature thought, ‘The teaching on the Body of Christ reveals itself to be decisive for fully understanding the conformation of the Christian to Christ through grace. Spiritually, there is no gap between Christ and His members, for he forms with them “a single mystical person”’.^{Footnote 67} The doctrine of the Body of Christ enables Aquinas to clarify Christ's active and intimate presence in every dimension of the Church. Whereas one might otherwise think of Christ's merit (or his meritorious satisfaction) as applying to others only extrinsically, in fact his merit spreads throughout his whole Body, since grace unites him so intimately with each and every one of his members. Although Torrell does not mention the Cross here, he does cite III, q. 48, a. 1, which is about Christ's Passion. Torrell goes on to point out that for Aquinas, Paul's epistles are in diverse ways about Christ's grace in light of the Mystical Body. The Church in Aquinas's vision is ‘before all else an organism of grace in total dependence on her head, Christ’.^{Footnote 68}

Commenting further on Christ and his Body the Church, Torrell notes that Aquinas conceives of Christ as priest, prophet, and king, and Christ's members share in his priestly, prophetic, and royal offices. Indeed, Aquinas is quite clear, in Torrell's words, that ‘since the Church-Body of Christ is an expression of his capital grace, all who are linked to him through baptism become kings, priests, and prophets with him’.^{Footnote 69} Torrell also treats the Body of Christ in the context of Aquinas's theology of the Holy Spirit, in which the Spirit is the bond of love both in the Trinity and in the Church. In this context, Torrell observes not only that Aquinas's ecclesiology centers around the doctrine of the Mystical Body, but also that the grace of the Holy Spirit is therefore at the heart of Aquinas's ecclesiology. The Church is formed by the grace flowing from the Head and constituting the Body. Torrell remarks that the Spirit perfectly unites the Head and the Body. He states that in Aquinas's view, ‘the role of the Holy Spirit is precisely to establish the “continuity” between Christ the Head and the faithful members, for he [the Spirit] has the property of remaining numerically one and the same in the Head and in the members’.^{Footnote 70} The Spirit plays the role of the soul in the Mystical Body. Like the soul in the human body, the Spirit in the Body of Christ is present ‘entirely in the Whole and entirely in each of its parts’, and the Spirit serves as the principle of the Body's unity and its source of holiness, and thus as the principle of the Body's spiritual life and fecundity.^{Footnote 71} Torrell reiterates that the Spirit, as the bond of love in the Trinity, unites the Mystical Body in the charity of Christ. Like blood in a corporeal body, charity is the ‘vital current’ that connects the whole Mystical Body as one ‘communion of saints’.^{Footnote 72} While it will be clear that Torrell has a rich and subtle understanding of Aquinas's theology of the Mystical Body, however, Torrell only once alludes to the Cross in relation to the Mystical Body and never mentions the Cross explicitly.

In a notable essay published in 2004, Herwi Rikhof argued persuasively for ‘the relevance of Thomas’ thought for present discussion of the Church’.^{Footnote 73} As Rikhof observes, the one image of the Church that Aquinas systematically develops is the image of the Body of Christ. Rikhof notes that when Aquinas attends to the Mystical Body, Aquinas focuses on unity and plurality, the role of the Holy Spirit (the ‘soul’ of the Body), and Christ as the Head. Rikhof does not mention the Cross of Christ, which will be my focus. He argues that for Aquinas, the Church is first of all a Trinitarian reality—the indwelling of the Trinity—and secondly ‘the Church is, basically, the community of believers’.^{Footnote 74}

Lastly from this period—given that in the previous section I examined the encyclical Mystici Corporis—let me very briefly sum up the portrait of the Mystical Body found in Vatican II's Dogmatic Constitution on the Church, Lumen Gentium. After completing his redemptive work, says Lumen Gentium, Christ poured out his Spirit and thereby constituted his Mystical Body. All who receive the sacraments, specifically baptism and the Eucharist, are united to Christ and comprise his Body. Through the Eucharist, believers ‘are taken up into communion with him and with one another’.^{Footnote 75} Lumen Gentium speaks about the diversity of members, functions, ministries, and gifts. The Holy Spirit functions analogously to how the soul functions in a human body, insofar as the Spirit unifies the diverse members into one Body by bestowing charity. Christ reigns as the Head of the Body. The members of the Body must be configured to him by suffering with him. While the Cross is not the heart of this portrait of the Mystical Body, it does contain a couple references to the Cross.

IV. Thomas Aquinas on the Cross and the Mystical Body

This final section will directly address Aquinas's theology of the Mystical Body. I will first treat some passages from his biblical commentaries, and then turn to the tertia pars of the Summa theologiae. My goal will be to display the Cross at the center of the Mystical Body, although Aquinas draws out other themes as well.

Commenting on Ephesians 2:16, where Paul praises Christ for reconciling Jews and Gentiles ‘in one body through the cross’, Aquinas observes that this ‘one body’ is the Church, the Body of Christ.^{Footnote 76} Aquinas cites Romans 12:5 as supporting evidence: ‘we, though many, are one body in Christ’—and, predictably, in his commentary on Romans 12:5, Aquinas in turn cites Ephesians 2:16 as supporting evidence. It is through the Cross that human beings have been reconciled to God and united as one Body. Aquinas also credits the Holy Spirit, poured out by Christ. He states, ‘This mystical body has a spiritual unity through which we are united to one another and to God by faith and love’.^{Footnote 77} In this regard he cites Ephesians 4:4, ‘There is one body and one Spirit’. This passage from Ephesians carries forward Paul's earlier discussion of ‘the blood of Christ’ by which Christ reconciled Jews and Gentiles ‘to God in one body through the cross’ (Eph 2:13, 16).

Another aspect of the Mystical Body is the diversity of the members’ gifts and functions. When Aquinas comments on 1 Corinthians 12, he focuses upon the diversity of gifts in the Body of Christ. As context for 1 Corinthians 12, recall 1 Corinthians 1–2, where Paul discusses the power of the Cross. Commenting on 1 Corinthians 1:18—’For the word of the cross is folly to those who are perishing, but to us who are being saved it is the power of God’—Aquinas explains what it means to be in Christ. Specifically, believers have discovered ‘in the cross of Christ God's power, by which he overcame the devil and the world: the lion of the tribe of Judah, has conquered (Rev 5:5)’.^{Footnote 78}

When Aquinas turns to 1 Corinthians 12:12—’For just as the body is one and has many members, and all the members of the body, though many, are one body, so it is with Christ’—he first reflects upon what it means to be ‘one’. He notes that a body is one because it has many members or organs: the body is made perfect by the presence of its diverse members, and therefore a body has perfect unity when it has all of its diverse members or organs. Analogously, Christ's Body has perfect unity through its many members. These members perform all the diverse functions needed for the Church's witness to Christ. In the sacrament of baptism, the Holy Spirit unites diverse human beings to Christ and establishes ‘the unity of the Church, which is the body of Christ’.^{Footnote 79} Some members follow the active life, some the contemplative; some are farmers, some teachers. Aquinas discusses offices in the Church, including the apostolic office, the office of prophecy, and the office of teachers, as well as those who perform miracles or speak in foreign tongues.

In the tertia pars of the Summa theologiae, Aquinas treats Christ as the Head of the Mystical Body. He inquires first into Christ's grace in relation to the hypostatic union, observing that ‘the habitual grace of Christ is understood to follow this union, as light follows the sun’.^{Footnote 80} Since the habitual grace of Christ perfects him as an individual, the question is how Christ can be the source of grace for all his members. Citing John 1:14-16 and Romans 8:29, Aquinas emphasizes that Christ is in fact the source of our grace. If he were not the source of grace for each of us, then he could not be the Head of the whole human race. His habitual grace, then, is of such plenitude that it serves as his grace of headship, overflowing onto the members of his Body. Aquinas comments that in an exterior manner, people can be the cause of the communication of grace to others through their leadership roles in the Church, as ‘heads’ of dioceses or of the whole Church. But no one can communicate interior grace other than Christ.^{Footnote 81}

As Head of the Mystical Body, Christ aims to perfect the Body. The ultimate source of this perfecting is the Cross. Aquinas explains, ‘To be a glorious Church not having spot or wrinkle is the ultimate end to which we are brought by the Passion of Christ’.^{Footnote 82} The reference here is to Ephesians 5:25-27, where Paul states that ‘Christ loved the Church and gave himself up for her, that he might sanctify her… [and] that he might present the Church to himself in splendor, without spot or wrinkle or any such thing, that she might be holy and without blemish’. According to Paul in Ephesians 5, just as husband and wife become one body or one flesh (Gen 2:24), so Christ and the Church are one body: ‘For no man ever hates his own flesh, but nourishes and cherishes it, as Christ does the Church, because we are members of his body’ (Eph 5:29-30). Aquinas states in commenting on Ephesians 5:25, ‘The sign of Christ's love for the Church is that “he delivered himself up for it”’; and he adds that Christ's sanctifying of the Church ‘is the effect of Christ's death’, not least because baptism has its ‘power from the passion of Christ’.^{Footnote 83}

In his discussion in the Summa theologiae of the effects of Christ's Passion, Aquinas makes explicit reference to the Mystical Body. Christ's Passion accomplishes its effects not for Christ (since Christ does not need healing from sin), but for us. Aquinas describes the effect of deliverance from sin: ‘Christ's Passion causes forgiveness of sins by way of redemption. For since he is our head, then, by the Passion which He endured from love and obedience, He delivered us as His members from our sins’.^{Footnote 84} Aquinas compares this to the way in which, in a human body, the hands may work to redeem an offense committed by the feet. He further explains, ‘For, just as the natural body is one, thought made up of diverse members, so the whole Church, Christ's mystic body, is reckoned as one person with its head, which is Christ’.^{Footnote 85} Therefore what the members have done—namely, sinned—is redeemed by what the Head does on the Cross. The action of the Head justifies the members, because the members have been united to the Head as his Body, through the grace of the Holy Spirit. As Aquinas says somewhat further on, although Christ's Passion in itself is superabundantly sufficient for the salvation of all human beings, ‘Christ's Passion works its effect in them to whom it is applied, through faith and charity and the sacraments of faith’.^{Footnote 86} Not only must sinners be joined to Christ's Body (and thereby share in the redemptive power of his Passion), but also sinners must be configured to Christ, as members to the Head.^{Footnote 87} This begins through baptism.

Aquinas treats these matters sometimes without mentioning the Mystical Body, but he mentions it often enough. For instance, in a reply to an objection, he remarks, ‘Christ's satisfaction works its effect in us inasmuch as we are incorporated with Him, as the members with their head…. Now the members must be conformed to their head’.^{Footnote 88} This configuration to Christ the Head is complex. Christ had a passible body and a graced soul, and through his Passion, he attained to immortality and glory. We, as his members, receive the salvific effects of his Passion, but we are not yet made immortal. This is because we must be configured to his Passion in our passible bodies. Aquinas states that we, ‘who are His members, are freed by His Passion from all debt of punishment’—which might seem to entail that we no longer will suffer or die.^{Footnote 89} But in fact we still do suffer and die. It is through being configured ‘to the sufferings and death of Christ’ that ‘we are brought into immortal glory’.^{Footnote 90} The members must follow the path taken by the Head. In this vein, Aquinas cites Romans 8:17, where Paul promises that we will be ‘fellow heirs with Christ, provided we suffer with him in order that we may also be glorified with him’.

In addition to the Cross, the Resurrection and Ascension are also central to the Mystical Body. Meditating upon the risen and ascended Christ's sitting at the right hand of the Father, Aquinas directs attention to Romans 8:11, where Paul states, ‘If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will give life to your mortal bodies also through his Spirit who dwells in you’. Aquinas here finds a connection between the Mystical Body—our union with Christ through the Spirit—and the exaltation (Resurrection/Ascension) of Christ. He avers, ‘Since Christ is our Head, then what was bestowed on Christ is bestowed on us through Him’.^{Footnote 91}

Paul maintains in Ephesians 2:6 that God has ‘raised us up with him [i.e. Christ], and made us sit with him in the heavenly places in Christ Jesus’. Discussing the Ascension, Aquinas comments that if our Head is ‘already raised up’, then, in a sense, we are already raised up with him, as his Body.^{Footnote 92} We have a foretaste of his risen life insofar as we are even now ‘in Christ’. In faith, we know that we will be raised and will ascend with Christ so as to sit with him at the right hand of the Father, that is, ‘in the heavenly places’. This will happen, says Aquinas, ‘for the very reason that Christ our Head sits there’.^{Footnote 93} For Aquinas, sitting at the right hand of the Father means being taken up into the Father's power and glory.^{Footnote 94} Here we should recall Christ's promise to the Church in Laodicea, ‘He who conquers, I will grant him to sit with me on my throne, as I myself conquered and sat down with my Father on his throne’ (Rev 3:21). The members of Christ's Body will share in what the Head alone fully possesses.

Aquinas also treats the Mystical Body in his account of Christ the Judge. At the Final Judgment, Christ will judge all humankind. While the entire Trinity will judge the world, wisdom is appropriated specially to the Word, and so judiciary power is attributed to Christ in particular. Drawing upon Augustine, Aquinas remarks that ‘judiciary authority is attributed to the Father, inasmuch as He is the Principle of the Son, but the very rule of judgment is attributed to the Son who is the art and wisdom of the Father’.^{Footnote 95} As man, Christ will judge the world, communicating the Trinity's judgment. Aquinas cites John 5:27, ‘For as the Father has life in himself, so he has granted the Son also to have life in himself, and has given him authority to execute judgment, because he is the Son of man’.^{Footnote 96} Aquinas contests Chrysostom's suggestion that Christ is Judge only as the divine Son, not as man. In response, Aquinas appeals to Christ's Headship of the Mystical Body. He states, ‘Christ even in His human nature is Head of the entire Church…. Consequently, it belongs to Him, even according to His human nature, to exercise judiciary power’.^{Footnote 97}

Christ judges in accordance with his priestly sacrifice and intercession. Citing Hebrews 4:15—’for we have not a high priest who is unable to sympathize with our weaknesses’—Aquinas highlights the point that Christ the Judge is not aloof from other humans but rather has shown intimate solidarity with them, preeminently through his suffering. As the true high priest, Christ ‘appeared once for all at the end of the age to put away sin by the sacrifice of himself’ (Heb 9:26). In the context of Hebrews, Aquinas affirms that ‘judiciary power belongs to the Man Christ on account of both His Divine personality, and the dignity of His headship, and the fulness of His habitual grace’.^{Footnote 98} Thus, although Aquinas does not say it explicitly here, Christ's Headship is that of the ‘high priest’ who, on the Cross, offered his life for our sins.

Let me add a word regarding the Eucharistic dimension of the Mystical Body. For Aquinas, at the heart of the sacramental order is Christ's Passion. It follows that the Cross is the ‘final cause’ (that is, the goal) of the ‘sacraments’ of the Mosaic Law.^{Footnote 99} With respect to the sacraments of the New Law of grace, Aquinas portrays the sacraments in terms of the distinction between a united instrument (Christ's humanity) and a separated instrument (the sacraments, moved by the united instrument). To understand the sacraments of the New Law, says Aquinas, we must recognize that ‘Christ's delivered us from our sins principally through His Passion’.^{Footnote 100} Sacraments unite us to the Cross's reconciling and deifying power. Aquinas comments that ‘the sacraments of the Church derive their power specially from Christ's Passion, the virtue of which is in a manner united to us by our receiving the sacraments’.^{Footnote 101}

Among the sacraments, the Eucharist has preeminence as the one to which all the others are directed.^{Footnote 102} Taken together, the seven sacraments are an integrated organism. Aquinas compares their role in the spiritual life to our bodily needs: baptism corresponds to generation and birth, confirmation to growing to maturity, the Eucharist to our daily nourishment, and so on.^{Footnote 103} In baptism, Aquinas says, the grace of the Holy Spirit and the fullness of the virtues are infused into the baptized person's soul, inaugurating the fullness of supernatural life and making the person a member of Christ's Body. Aquinas here again cites John 1:16, combined with a text from Augustine crediting baptism with incorporating people into Christ's Body. Reiterating that ‘the fulness of grace and virtues flows from Christ the Head to all His members’, Aquinas explores what this means for baptism.^{Footnote 104} He underscores baptism's constitutive relation to the Mystical Body. As he states, ‘By Baptism man is born again unto the spiritual life…. Now life is only in those members that are united to the head, from which they derive sense and movement. And therefore it follows of necessity that by Baptism man is incorporated in Christ, as one of His members’.^{Footnote 105} Aquinas describes this ‘sense and movement’ as knowledge of the true faith (‘sense’) and the ‘instinct of grace’ (‘movement’) making it possible to perform virtuous acts.^{Footnote 106} To be a member of Christ's Body is to have this supernatural life.

Baptism incorporates us into Christ's Body, and the Eucharist completes our fellowship or communion with Christ, since we receive Christ himself and are changed, as it were, into Christ.^{Footnote 107} Through baptism we are ‘born anew in Christ in virtue of His Passion’, and through the Eucharist we are ‘made perfect in union with Christ Who suffered’.^{Footnote 108} In these sacraments, the Cross is at the center of our incorporation into and union with Christ as members of his Mystical Body.

Let me conclude this discussion of Aquinas on Christ's Mystical Body by directing attention to Aquinas's discussion of the efficient causality of Christ's Passion—question 48 of the tertia pars. Aquinas reiterates that ‘grace was bestowed upon Christ, not only as an individual, but inasmuch as He is the Head of the Church, so that it might overflow into His members’.^{Footnote 109} To this point, he adds a surprising claim. He says that the unity of the Mystical Body is so profound that ‘Christ's works are referred to Himself and to His members in the same way as the works of any other man in a state of grace are referred to himself’.^{Footnote 110} When Christ dies on the Cross, his action belongs (in its merit) not only to Christ, but to his members. He acts on our behalf in the fullest possible sense, in such a way that, because we are members of his Body, we can be said to merit in his action. Aquinas lays down a radical principle, one that is indebted to Augustine (and St Paul): ‘The head and members are as one mystic person; and therefore Christ's satisfaction belongs to all the faithful as being His members’.^{Footnote 111} The Cross is at the center of the Mystical Body, because believers are ‘one mystic person’ with Christ on the Cross.