That the liturgical reform does not constitute a break, but a constant in the history of the Church, is a true assertion. The Church is not an immobile body, nor is the liturgy a petrified reality. From the early centuries, Catholic prayer and the sacramental renewal of the Sacrifice of Calvary have known developments, enrichments, and legitimate adaptations. The problem arises when this general truth becomes an indeterminate principle, capable of justifying any concrete configuration of the rite, even those that introduce a problematic relationship with the immediately preceding tradition. Because then the reform ceases to be a theological criterion and becomes a hermeneutical alibi. And reform as a theological category demands limits.
The Church has always reformed, yes, but not in any way or in any sense. Authentic reform has traditionally been understood as purification, refinement, and consolidation of a received tradition, not as a global substitution of one ritual form for another.
This is crystal clear in the case of the Missal of St. Pius V. The bull «Quo primum» does not inaugurate a new liturgy; it fixes one that already existed. It does not inaugurate a creative process; it puts an end to a recent dispersion. And it does so, moreover, with a criterion that should not be forgotten: antiquity as a guarantee of legitimacy. That is why it is methodologically fallacious (or ignorant?) to invoke St. Pius V to support a conception of liturgical unity that he did not apply. If the objective had been absolute uniformity, venerable rites with more than two centuries of antiquity would not have been preserved. The unity sought by Trent was doctrinal and sacramental, not expressive in a rigid sense.
The implicit analogy between the liturgical fragmentation prior to Trent and the current coexistence of the 1962 Missal with the Missal promulgated after the Second Vatican Council does not withstand minimally serious analysis. In the 16th century, liturgical fragmentation was associated with a greater or lesser doctrinal break conveyed in strange innovations and, in many cases, with an eroded Eucharistic theology. Today, on the other hand, celebration according to the 1962 Missal introduces no doctrinal novelty but maintains perennial doctrine; nor does it express an alternative ecclesiology, but the Catholic one; nor does it constitute an objective threat to sacramental communion, because it strengthens it. What exists today is not fragmentation, but internal continuity within the same Roman rite. And treating that continuity as if it were an anomaly reveals a shift in the very understanding of Tradition.
Organic development is more than a chronological succession. The term is correct only if understood rigorously. A development is organic when it maintains the identity of the subject that develops. In biology, an organism that ceases to be recognizable has not developed: it has transformed into something else. Applied to the liturgy, this means that development cannot imply a practical disauthorization of the immediately preceding form, and even less so of a form that has been normative for the Church’s prayer for centuries and has sustained the faith of all our forebears. Here lies the importance of Benedict XVI’s assertion that the traditional liturgy was never abolished. It is not a secondary juridical matter, but a major ecclesiological principle: the Church cannot declare its own multisecular prayer problematic without eroding its historical credibility.
That is why liturgical unity is an ecclesiological concept. When today the coexistence of liturgical forms is presented as a threat to unity, it is worth asking what is exactly meant by unity. If unity means absolute expressive uniformity, then the history of the Church appears, retrospectively, as a permanent anomaly. But if unity means communion in faith, in the sacraments, and in legitimate authority, then ritual diversity, when it is traditional and doctrinally sound, is not only not a problem, but has always been a richness.
The current difficulty is not primarily liturgical, although the liturgy is its most indicative and evident exponent. The punctum dolens is the notion of Tradition, undeniably Catholic. And if history is not linear and development is not univocal, Tradition cannot be enclosed in a single moment of time.
Only from such a premise is the coexistence of both missals accepted as a criterion of ecclesial maturity, as Benedict XVI masterfully argued in his motu proprio Summorum Pontificum and in the letter with which he presented it. From this perspective, the freedom to celebrate with the 1962 Missal (with which all the saints have celebrated the Latin rite for more than five centuries) is not an uncomfortable pastoral concession, but an absolutely logical criterion, to despise which supposes making a mockery of the first foundation of metaphysics: the principle of non-contradiction. That today any priest of any age from any diocese can naturally celebrate the Mass of our forebears—that of the Council of Trent and Vatican II—demonstrates that the Church, semper reformanda sed semper idem, recognizes itself across time without amputating stages of its own organic development.
St. Pius V defended unity by safeguarding the ancient. Benedict XVI defended unity by reconciling the Church with itself. Both acted from the same conviction: that Tradition is not an obstacle to communion, but its condition.
The true question, therefore, is not why coexistence is problematic today, but what conception of Tradition makes it so. And that question is not answered with generic appeals to reform, but with a theology of the liturgy that does not renounce the living memory of the Church. Unless the question is… whether there is truly a notion of Tradition.