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East and West can easily continue dialogue also as regards the Filioque question providing there is full acceptance of the doctrine of tradition on the monarchia of the Father. The monarchia of the Father means that the Father is the sole origin and cause both of the Son and of the Spirit.

This is a very valuable statement on the thorny issue of the Filioque, which clarifies many aspects of the position of the Roman Catholic theology on this matter. I am sure that this statement will play a very important role in the official theological dialogue between the Roman Catholic and the Orthodox Church when it comes to the point of discussing this issue. My reaction as an Orthodox theologian to this document can be summarized in the following observations:

1. It is with deep satisfaction that I read in the document the emphatic assertion that no confession of faith belonging to a particular liturgical tradition can contradict the expression of faith of the Second Ecumenical Council (Constantinople 381) which has been taught and professed by the undivided Church. This is a very good basis for discussion.

2. It is extremely important, in my judgment, to clarify the point concerning the “source” (????) or “principle” (?????) or “cause” (?????) in the Holy Trinity. This is crucial perhaps decisive. The document of the Vatican sees no difference between the monarchia of the Father, i.e. the idea that the Father is the sole “principle” in God’s Trinitarian being, an idea strongly promoted by the Greek Fathers, and St. Augustine’s expression that the Holy Spirit proceeds from the Father “principaliter”. However, before we can come to the conclusion that the two traditions, Eastern and Western, understand this matter in the same way, we must raise the following questions:

a) Does the expression “principaliter” necessarily preclude making the Son a kind of secondary cause in the ontological emergence of the Spirit? The Filioque seems to suggest two sources of the Spirit’s personal existence, one of which (the Father) may be called the first and original cause (principaliter), while the other one (the Son) may be regarded as a secondary (not principaliter) cause, but still a “cause” albeit not “principaliter”.
The discussions both at the time of St. Photius and at Lyons and Florence-Ferrara seem to have paid special attention to this delicate point. It is not accidental that the Greek theologians ever since the time of Photius insisted on the expression: