Dear brothers and sisters in Christ,
I had the occasion to study the matter more deeply then before, thanks to an Italian RC forum, so I will propose this reading of the Catechism of the Catholic Church, where the matter of Consecration at the Eucharist is faced directly.
Article 1333 thus says:
"At the heart of the Eucharistic celebration are the bread and wine that, by the words of Christ and the invocation of the Holy Spirit, become Christ's Body and Blood. Faithful to the Lord's command the Church continues to do, in his memory and until his glorious return, what he did on the eve of his Passion: "He took bread...." "He took the cup filled with wine...." the signs of bread and wine become, in a way surpassing understanding, the Body and Blood of Christ; they continue also to signify the goodness of creation. Thus in the Offertory we give thanks to the Creator for bread and wine, fruit of the "work of human hands," but above all as "fruit of the earth" and "of the vine" - gifts of the Creator. the Church sees in the gesture of the king-priest Melchizedek, who "brought out bread and wine," a prefiguring of her own offering"
As you can see, the official understanding of the CCC is that both Epiclesis and Words of Institution co-operate in the transubstantiation, exactly as you Orthodox hold. The certainty of the change, thus, is given at the Elevation, when all conditions have been fulfilled. What about the Latin Vetus Ordo, then? Where's the Epiclesis there?
Well, there's an Epiclesis right before the Words of Institution in the Latin Mass, saying thus:
"Quam oblationem tu, Deus, in omnibus, quaesumus, benedictam+, adscriptam+, ratam+, rationabilem+, acceptabilemque+ facere digneris, ut nobis Corpus+, et Sanguis+ fiat dilectissimi Filii tui Domini nostri Jesu Christi"
"O God, deign to bless + what we offer, and make it approved, + effective, + right, + and wholly pleasing in every way, that it may become for our good, the Body + and Blood + of Your dearly beloved Son, our Lord Jesus Christ. "
In the Vetus Ordo, the Holy Spirit is implicitly referenced as God
, which is a proper name since He is one of the Blessed Trinity and God in fulness, soI don't see any need to make it more explicit if the tradition of the Latin Catholic Church never needed it.
In the Novus Ordo, the Epiclesis is identical at least in the Latin version of the Ordo Missae. The problem is in the specific liturgies as translated in the local Episcopal Conferences.
In the Italian adaptation, for example, the most common version in use of the Canon Missae has a much more explicit Epiclesis then the Latin edition, saying (I translate it for you) "Truly holy Father, source of all holiness, sanctify these gifts with the effusion of Thy Spirit, so that they become for us the Body + and Blood + of Jesus Christ our Lord".
Now, the question raises spontaneously: why does the Tridentine Council underline so much that the Consecration is performed at the Words of Institution, if the Epiclesis is also necessary? Since both elements must occur - I mean Epiclesis and Words of Institution - the change occurs only when both of them are performed. Now, in the Latin Canon Missae (presumably the only one of interest at the Council of Trent!) had the Words of Institution following the Epiclesis. That gives us a good reason why in the Latin Mass (both Vetus and Novus Ordo) the Consecration occurs only at the Words of Institution. In the Eastern Rites - who had been largely ignored as "notable exceptions" up to the Second Vatican Council, the same requirement of having both conditions satisfied is reconciled with the opposite order, i.e. the Words of Institution preceeding the Epiclesis. The latter, in this case, "completes"what the Words of Christ have prepared, while the opposite occurs in the Latin Mass.
Now, here's a quote from the Wikipedia (the sources are accurate, this time) about the Holy Qurbana of Addai and Mari:
"The words of Eucharistic Institution are indeed present in the Anaphora of Addai and Mari, not in a coherent narrative way and ad litteram, but rather in a dispersed euchological way, that is, integrated in successive prayers of thanksgiving, praise and intercession".
The quote is taken from the Pontifical Council for Promoting Christian Unity, and thus has Pontifical authority. Here's the interesting affirmation of the Wikipedia, which I consider of a noticeable value:
The anaphora contains, for instance, the declaration: "The body of Christ and his precious blood are on the holy altar." This has been compared to the Eastern Orthodox Church declaratory formula for absolution: "The servant of God N. is absolved", in contrast to the Western "I absolve thee". A similar contrast is found in the Eastern and Western formulas for baptism.
This will explain many things. The Words of Institution have been nevertheless added into the text of the Holy Qurbana of Addai and Mari since the 1900s, but after the studies and documents of the aforemantioned Pontifical Council have been released, the Chaldean Catholic Church is transitioning towards the restoration of one of the oldest rites of the Catholic Church into its primordial form; this is provoking some un-christian reactions from Traditionalist Catholics, but I won't pay too much attention to it. Since such a document has been released with the approval of a Traditionalist Pope such as Benedict XVI, and I don't see any reason, as a Traditionalist myself, to discuss the validity of that rite from the POV of sacramental grace.
In Christ, Alex