Auctoritates · ad fol. iii
nn. 90–94
Venite ad me · De Liturgia
ad fol. iii · n. 92 · videtur, sed contra, respondeo: the Council, Pius XII and the Code, reported
Videtur quod
It would seem that whatever is prayed is by that fact fixed as belief; for the Indiculus says that the law of praying establishes the law of believing.
Sed contra
Mediator Dei 48
lex credendi legem statuat supplicandi
Pius XII says that popes and councils, defining a revealed truth, have often drawn arguments from the liturgy, as Pius IX did for the Immaculate Conception, and that the Church and the Fathers looked to the ancient rites when a truth was in doubt: hence the maxim legem credendi lex statuat supplicandi. But the liturgy, he says, does not of itself and on its own decide what is of Catholic faith. Since it also confesses truths that are eternal, it is subject to the Church’s supreme magisterium, and can give proof and witness of no small weight toward settling a point of doctrine.
Put absolutely, he says, the relation runs the other way, lex credendi legem statuat supplicandi: the rule of belief sets the rule of prayer; and so with hope and charity, in which we pray always.
Sacrosanctum Concilium 14
plenam … consciam atque actuosam participationem
The Council says the Church desires that all the faithful be led to the full, conscious and active participation that the nature of the liturgy itself requires, which belongs to the baptized by right and duty as a chosen race and a royal priesthood (1 Pet 2:9). This participation, it says, is the first aim of the reform, the primary and indispensable source of the true Christian spirit, and pastors are to pursue it by instruction in all their work.
Yet it holds out no hope of this unless the pastors are first steeped in the liturgy’s spirit and power, so that the liturgical formation of the clergy comes first of all.
Respondeo
I answer that the prayer is a witness and the faith is what it witnesses. Read forward, as the Indiculus argues, the axiom stands; read backward, with the prayer fixing a doctrine, it is refused (fol. iii, the checker). And a participation that hands the faith on must be conscious, and so formed.
Tabula VI · Semel tradita
Two buffers in a ring, each feeding the other: the Indiculus has the law of praying establish the law of believing, Mediator Dei 48 has the law of believing establish the law of praying. A cell like this holds its bit only because each half keeps telling the other what it is. Pushed once, on credendi, the other follows a step later and both stay: semel traditae sanctis fidei (Jude 3).
Reported, not reproduced · the texts are at vatican.va
What is it