«MYSTICI CORPORIS». - Opening words of the encyclical issued by Pius XII on 29 June 1943 (AAS, 36 [1943], pp. 193-248), in which the doctrine of the Mystical Body is expounded. The Pope was moved to promulgate this solemn document by a special memorandum from Konrad Gröber, Archbishop of Freiburg (Breisgau), addressed to the Holy See and to the German bishops, concerning errors that had spread in Germany on this subject (cf. J. Froger, L’encyclique Mediator Dei, in La pensée catholique. Cahiers de synthèse, 7 [1949], pp. 56-76, especially pp. 65-66 where § II of Gröber’s letter is quoted, in which the doctrinal exaggerations regarding the Mystical Body are clearly indicated). The encyclical is a precise and detailed response to the individual points in question, though generally presented in an implicit manner, as an aside within a broader discourse; indeed, in the serene unfolding of its imposing doctrinal structure, the response acquires particular persuasive force for those who had erred and special probative vigour for those who remained within the bounds of orthodoxy.
The encyclical begins with the concept of the Church as a body, highlighting its prerogatives: one, undivided, visible, organically and hierarchically unified, endowed with means of sanctification (the Sacraments) and composed of specific members (not excluding sinners); it then demonstrates that this body is Christ’s «corpus Christi», because Jesus Christ is a) its founder: through His evangelical preaching, the redemption of the Cross, and the promulgation on the day of Pentecost; b) its head: by reason of His supreme dignity, His invisible and visible governance (through the Pope and bishops), the mutual interdependence, the conformity of nature and grace with the body, the fullness of supernatural charisms, and His influence on the entire organism through ontological (sanctifying) and psychological (illuminating) channels; c) its sustainer, through His ministers who build from without, and the Holy Spirit, who as the soul of the Mystical Body is its internal principle of cohesion and regulator of all vital currents; d) its saviour, since He acquired all the members of the Church by His Blood (Part I). From these relationships of Christ with the Church there emerges the intimate, mysterious union of all the faithful with Jesus, whose bonds—juridical, social, psychological, ontological, and sacramental, especially Eucharistic—are illustrated (Part II). As a corollary to the matter expounded, the Pope condemns false mysticism and quietism, as well as certain errors regarding confession and prayer, concluding with a warm appeal to love the Church (Part III). A moving epilogue on Mary as Mother of the Mystical Body brings the great document to a close.
In the encyclical, there are frequent assertions of extraordinary theological importance, almost as if they were pronouncements of greater weight from the Magisterium in modern ecclesiology, e.g.: the identity of the Mystical Body with the Roman Catholic Church, the conditions for being a member of the Church (v.), the condemned vivisection between «Rechtskirche» (Church of law) and «Liebeskirche» (Church of love), the Holy Spirit as the soul of the Mystical Body, the close relationship between the internal and external governance of the same organism, the theandric character of ecclesiology, and the condemnation of any form of pancristism (against Pelz), with Mary as Mother of the Church.
This distinguished document is the glorious culmination of a movement that, taking shape in Germany through the work of J. A. Möhler (v.), influenced all nineteenth-century ecclesiology (C. Passaglia, Cl. Schrader, J. B. Franzelin, M. J. Scheeben), as an implicit response to the materialistic conception of human solidarity. When, after the war of 1914-18, the Catholic and Marxist conceptions confronted each other across Europe, almost as an ideological and chronological coincidentia oppositorum, the theme of the Mystical Body was once again keenly felt: works of broad erudition and aimed at constructive synthesis arose (J. Anger, F. Jürgensmeier, Feckes, Wickenhauser, Grivč, E. Mura, Koster, E. Mersch, L. Malevez, S. Tromp, Congar). Amid such a ferment of studies, enthusiasms and intemperances of form and substance are to be explained. The encyclical gathers and valorises the best data of this theology in fieri, does not stifle the movement but strengthens it by eliminating its principles of dissolution; it concludes one epoch of ecclesiastical theology and inaugurates another, more secure and more fruitful.