Excerpt from God, History, and Dialectic by Most Rev. Photius (Joseph P.) Farrell, S.S.B., D.Phil.(Oxon.):
When St. Augustine wrote his De Trinitate, he may have done so partially in an effort to combat Arianism. Certainly the Council of Toledo advanced Augustine’s arguments for the filioque as being anti-Arian in nature. But is the filioque in fact an adequate safeguard against Arianism? We have seen that the Arians defined deity by confusing the hypostatic feature of the Father, ingenerate causation, with the divine essence itself: they defined the divine essence by the Father’s personal feature. Thus, they could deny that Christ was fully God because he did not cause but was caused. To this we saw that Athanasius’ response is to go to the root of the heresy: the definition of the divine essence as causation; if that were so, he said, then, yes, the Son in order to be God would have to cause the Spirit, and the Spirit a fourth person, and so on until on ended in Polytheism.
But it is exactly this course which Augustine pursues:
“As the Father hath life in Himself, so hath He given to the Son to have life in Himself.”(De Trinitate, 7:3:5)Because of this, one should, says Augustine:
“understand that as the Father has in Himself that the Holy Spirit should proceed from Him so He has given to the Son that the same Spirit should proceed from Him(the Son), and both apart from time. For if the Son has of the Father whatever He (the Father) has, then certainly He has of the Father that the Holy Spirit proceeds also from Him.”(Ibid., 15:27:47)
The phrase “and both apart from time” indicates very clearly that Augustine is not talking about a mere sending of the Spirit from or through the Son in respect of time, that is, in respect of Economy or of God’s providential ordering and relationship with His creation. This is a clear confession of a procession of the Spirit from the Father and the Son in eternity, in Theology. Notice that there is a new structural element, a new turning in Augustine’s ordo theologiae, and that is the element of a subordination of persons to attributes: we have now arrived at the full-blown Augustinian ordo theologiae of essence, attributes, persons, for the Son, as has been stated by Augustine, receives His causation of the Spirit from the Father not on the basis of a direct deduction from the simplicity of their essence, but mediately, on the basis of their common interchangeable attributes. The reason for this step is, I believe, rather obvious, for had Augustine argued immediately from the simplicity to the Persons, he would have ended with no persons at all; it is this middle step which disguises the problem from him. Thus, there are two types of subordinationist structures present in Augustine’s exposition of doctrine: the first, the purely formal and structural level, is that of the Augustinian ordo theologiae itself: essence, attributes, persons.
The second is that which occurs within the category of Persons, for the Holy Spirit is seen to proceed from an Uncaused Cause, the Father, and the Caused Cause, the Son, in almost the identical manner that Plotinus’ World-Soul proceeded both from the One and the Nous.
But is Augustine, the great expositor of the doctrine of the Trinity really that confused about these categories? Indeed, and unfortunately, yes:
“For we cannot say that the Holy Spirit is not life, while the Father is life, and the Son is life: and hence as the Father … has life in Himself; so He has given to Him (the Son) that life should proceed from Him, as it also proceeds from himself.” (De Trinitate, 15:27:48)
Hence, not only has the unique personal distinction of the Father been exchanged with the Son on the basis of the common attribute of life, but that attribute which proceeds from the Father and the Son turns out to be the Holy Spirit. It is precisely that Holy Spirit who turns out to be the attribute common to both the Father and the Son; consequently, a person has been confused with an attribute of all three persons; what is natural is now personal and the distinction of Person and Nature has entirely broken down. This is, of course, classical Sabellianism.
This is a self-defeating enterprise at best, for having made the Spirit proceed from the Father and the son because the Father and the Son share common attributes since the essence is simple, the Spirit then becomes an attribute, defines the essence, indeed, is the essence, and therefore, is the new principle of unity in the Trinity! Does Augustine actually say this? Indeed:
“Because both the Father is a spirit and the Son is a spirit, and because the Father is holy and the Son is holy, therefore… since the Father, the Son, and the Holy Spirit are one God, and certainly God is Holy, and God is a spirit, the Trinity can be called also the Holy Spirit.”(De Trinitate, 5:11:12)
Thus, since the Spirit defines attributes suitable to Father and Son, He becomes the new locus of unity in the Trinity — note now the Monarchy of the Father is destroyed as the personal locus of unity of the Trinity — and is thus the Hegelian “Synthesis” to the Father’s “Thesis” and the Son’s “Antithesis”, he is, in Augustine’s words, “the substantial and consubstantial love of both.”(De Trinitate, 15:27:50) And this, of course, is the ultimate statement of a dialectical vision of God, for now the Persons are not distinguished by relations of origin, but of opposition.