I now come to the positive reason which motivated my decision to issue this Motu Proprio updating that of 1988. It is a matter of coming to an interior reconciliation in the heart of the Church. Looking back over the past, to the divisions which in the course of the centuries have rent the Body of Christ, one continually has the impression that, at critical moments when divisions were coming about, not enough was done by the Church’s leaders to maintain or regain reconciliation and unity. One has the impression that omissions on the part of the Church have had their share of blame for the fact that these divisions were able to harden. This glance at the past imposes an obligation on us today: to make every effort to enable for all those who truly desire unity to remain in that unity or to attain it anew. [Letter to Bishops accompanying Summorum Pontificum]
Art 1. The Roman Missal promulgated by Pope Paul VI is the ordinary expression of the lex orandi (rule of prayer) of the Catholic Church of the Latin rite. The Roman Missal promulgated by Saint Pius V and revised by Blessed John XXIII is nonetheless to be considered an extraordinary expression of the same lex orandi of the Church and duly honoured for its venerable and ancient usage. These two expressions of the Church’s lex orandi will in no way lead to a division in the Church’s lex credendi (rule of faith); for they are two usages of the one Roman rite. [Summorum Pontificum Art 1.]
For that matter, the two Forms of the usage of the Roman Rite can be mutually enriching: new Saints and some of the new Prefaces can and should be inserted in the old Missal. The “Ecclesia Dei” Commission, in contact with various bodies devoted to the usus antiquior, will study the practical possibilities in this regard. The celebration of the Mass according to the Missal of Paul VI will be able to demonstrate, more powerfully than has been the case hitherto, the sacrality which attracts many people to the former usage. The most sure guarantee that the Missal of Paul VI can unite parish communities and be loved by them consists in its being celebrated with great reverence in harmony with the liturgical directives. This will bring out the spiritual richness and the theological depth of this Missal. [Letter to Bishops accompanying Summorum Pontificum].With the passage of time since 2007, it appears to me that those promoting the celebration of the Extraordinary Form have become increasingly open about the selective way in which they wish to implement Summorum Pontificum. They are happy to take the easier access to such celebrations - but they do not accept the indications in Pope Benedict's letter with regard to the position of the Missal of Paul VI, the notion of mutual enrichment or the idea that the two forms of the one Roman Rite are equally "of tradition". This was expressed quite explicitly recently on the blog of the Chairman of the Latin Mass Society, and his citation of Michael Davies is suggestive of how far this attitude towards contemporary ecclesial life may be systemic among traditionalist Catholics:
What is significant about a document from Rome is what it changes, not what it says. This is an exegetical principle of the late Michael Davies: when reading a new document, ask What does it allow which was not previously allowed? What does it forbid which was not previously forbidden? The rest is padding. The truth of this principle becomes clear with the assistance of hindsight. What is significant about Paul VI's Memoriale Domini is that it allowed Communion in the Hand: it is irrelevant that nine tenths of the thing is hymn of praise for Communion on the Tongue, and that it actually says that the existing rules aren't being changed. That 90% of the document is inert, like the polystyrene padding in a parcel. In exactly the same way, what is significant about Summorum Pontificum is that the Traditional Mass is allowed without permission from bishops. The rhetorical concessions to liberals unhappy about this, slipped in here and there, are of no significance. Getting worked up about them is a complete waste of time.As far as the Liturgy goes this may not be leading to great division within the Church, though it is not likely that it genuinely promotes that "reconciliation in the heart of the Church" desired by Pope Benedict. The vast majority of us continue to use the Missal of Paul VI; and the typical parishioner is highly unlikely to be affected in any way by Summorum Pontificum.
However, the stakes are much higher with regard to the rumoured reconciliation of the Society of St Pius X in the form of a Personal Prelature. According to the interview with Archbishop Pozzo in La Croix, (according to the account given here as I am not able to find the link to the original):
"The difficulties raised by the SSPX concerning the Church-State relationship and religious freedom, the practice of ecumenism and dialogue with non-Christian religions, certain aspects of the liturgical reform and its concrete application, remain subject to discussion and clarification but do not constitute an obstacle to a canonical and juridical recognition of the SSPX.
"The documents of the Second Vatican Council must be received with the required degree of adherence.
"The acceptance of the texts on relations with other religions is not a prerequisite for the canonical recognition of the Lefebvrist society, and certain questions can remain 'subject to discussion and clarification'." Anticipating already a canonical recognition —for which he has been working since 1987— the prelate announces that the Second Vatican Declarations "will, even after the canonical recognition, remain subject to discussion and deeper study, in order to obtain greater precision and avoid the misunderstandings or ambivalences that we know to have spread throughout today’s ecclesial world.”
According to Abp. Pozzo, the SSPX is requested "to accept that the Magisterium of the Church is the only one entrusted with guarding, defending and interpreting the deposit of the Faith".If traditionalist Catholics take the same attitude to this reconciliation, should it occur as rumoured, as they have taken to Summorum Pontificum, they will rejoice at the establishment of the Personal Prelature........and consider any accompanying affirmations of the necessity of fidelity to the teaching of the Second Vatican Council to be of no account. Archbishop Pozzo's diplomatic use of the words "discussion" and "clarification" should not hide the fact that there is doctrinal disagreement here.
The very real danger is that, should a regularization of the canonical situation of the SSPX take place before the issues relating to the teaching of the Second Vatican Council are resolved, traditionalist Catholics will take it as a green light to dissent from that teaching and from the teaching of subsequent Popes. Rather than achieving a "reconciliation at the heart of the Church" it will contribute to an institutionalising of a division at the heart of the Church.