the point that the Roman Church tried to make was to point out the necessary relational distinction between the Son and the Holy Ghost.
Keep these three fundamental tenets in mind:
- The essential distinction that makes each Person of the Blessed Trinity distinct is relational, which is a distinction that deals mostly with the mode of procession (e.g. x proceeds from y).
- The Second Person of the Blessed Trinity is essentially the manifestation of God’s infinite and perfect intellectual act (generation); the Third Person of the Blessed Trinity is likewise the manifestation of God’s infinite and perfect charitable act [act of love] as reciprocated by the Son (spiration).
- The Son of God the Father, as the Second Person of the Blessed Trinity made man, proceeds from God the Father independently of God the Holy Ghost.
The Orthodox presentation of the teaching results in a lack of any essential distinction between God the Son and God the Holy Ghost; both proceed from God the Father independently of the other such that both are relatively and relationally identical to the Father.
But if the distinction between the Persons is essentially relational, yet the Second and Third Persons are both relationally identical to the Father, then there are only two distinct Persons of the Trinity, which utterly destroys the rationality of the dogma. Put another way: If we contend that the Persons of the Trinity are “really distinct,” and the only metaphysical difference between the Persons (which difference makes them “really distinct”) is in their distinct modes of relationship to the Father, but both the Son and Spirit have the exact same relationship to the Father, then both the Son and Spirit are not truly distinct; rather, they are identical persons that become indistinguishable, and thus there are only two distinct Persons of the Blessed Trinity.
Hence, the Roman Church teaches that a relational distinction between the Father-to-Son relationship and Father-to-Spirit relationship is necessary to distinguish the Person of the Son (relative to the Father) from the Person of the Spirit (relative to the Father).
Therefore, the “filioque” phrase was used to designate the procession of the Spirit from the Father through the Son in a way that makes the spiration of the Spirit a consequence (as it were) of the generation of the Son from the Father.
Metaphysically, there can be no other solution if one understands the nature of the persons. Since love proceeds from knowledge, and not knowledge from love (there can be no love without knowledge of the object of that love), we can understand why Scholastic theologians support the idea that the Son proceeds from the Father as a manifestation of the intellectual act of God (generation).
The procession of the Spirit from the Father through the Son is, therefore, a manifestation of the reciprocal and mutual exchange of love between the Father and the Son predicated and dependent upon Their perfect knowledge of Each Other, not in the order of time but in the order of logical sequence (spiration).
In the order of this logical sequence, the Father must first intellectually conceive of the Son before loving Him, and only as a consequence of His procession can the Son reciprocate an identical love, since, the Father and Son being equal, are also equal in the love spirated from Them, again, not in the order of time, but in the order of logical sequence.