MEDIATOR DEI
ENCYCLICAL OF POPE PIUS XIION THE SACRED LITURGY
TO THE VENERABLE BRETHREN, THE PATRIARCHS, PRIMATES,
ARCHBISHOPS, BISHIOPS, AND OTHER ORDINARIES
IN PEACE AND COMMUNION WITH THE APOSTOLIC SEE
25. It is an error, consequently, and a mistake to think of the sacred liturgy as merely the outward or visible part of divine worship or as an ornamental ceremonial. No less erroneous is the notion that it consists solely in a list of laws and prescriptions according to which the ecclesiastical hierarchy orders the sacred rites to be performed.
26. It should be clear to all, then, that God cannot be honored worthily unless the mind and heart turn to Him in quest of the perfect life, and that the worship rendered to God by the Church in union with her divine Head is the most efficacious means of achieving sanctity.
27. This efficacy, where there is question of the eucharistic sacrifice and the sacraments, derives first of all and principally from the act itself (ex opere operato). But if one considers the part which the Immaculate Spouse of Jesus Christ takes in the action, embellishing the sacrifice and sacraments with prayer and sacred ceremonies, or if one refers to the "sacramentals" and the other rites instituted by the hierarchy of the Church, then its effectiveness is due rather to the action of the church (ex opere operantis Ecclesiae), inasmuch as she is holy and acts always in closest union with her Head.
28. In this connection, Venerable Brethren, We desire to direct your attention to certain recent theories touching a so-called "objective" piety. While these theories attempt, it is true, to throw light on the mystery of the Mystical Body, on the effective reality of sanctifying grace, on the action of God in the sacraments and in the Mass, it is nonetheless apparent that they tend to belittle, or pass over in silence, what they call "subjective," or "personal" piety.
29. It is an unquestionable fact that the work of our redemption is continued, and that its fruits are imparted to us, during the celebration of the liturgy, notable in the august sacrifice of the altar. Christ acts each day to save us, in the sacraments and in His holy sacrifice. By means of them He is constantly atoning for the sins of mankind, constantly consecrating it to God. Sacraments and sacrifice do, then, possess that "objective" power to make us really and personally sharers in the divine life of Jesus Christ. Not from any ability of our own, but by the power of God, are they endowed with the capacity to unite the piety of members with that of the head, and to make this, in a sense, the action of the whole community. From these profund considerations some are led to conclude that all Christian piety must be centered in the mystery of the Mystical Body of Christ, with no regard for what is "personal" or "subjective, as they would have it. As a result they feel that all other religious exercises not directly connected with the sacred liturgy, and performed outside public worship should be omitted.
30. But though the principles set forth above are excellent, it must be plain to everyone that the conclusions drawn from them respecting two sorts of piety are false, insidious and quite pernicious.