Below is an extensive citation from Dr. Swete’s book The Holy Spirit in the Ancient Church: A Study of Christian Teaching in the Age of the Fathers (Page 367-71). I thought it was an interesting summation of his own pneumatology which he had spent years on throughout the course of his life. That he is Anglican is abundantly clear, for when he comments on the dogmatic Filioque which is taught by the Latins to have lacked any ecumenical support, he is, in fact, severing the pneumatology of the Eastern and Western Fathers, which was not the wanted conclusion of either the Latins or the Greeks in the re-union Councils. This would imply his holding to the Branch theory of Church unity, where there can be a divergence in faith, and yet one undivided body of the Lord. Aside from that, his synthesis on the matter is quite interesting.
” The New Testament teaches that the Holy Spirit is the Spirit of both the Father and of the Son. The ancient Church understood this to mean that He belongs essentially to both. Since the Son is of one substance with the Father, and has all things that the Father has, He has the Spirit of the Father for His own. The Spirit is the Son’s own (ίδιον) as He is the Father’s own. He is in the Son, as He is in the Father, in the way of essence and nature (ούσιωδώς, φυσικώς). He rests and abides in the Son; He is the image of the Son, as the Son is the image of the Father; He was sent by the Son from the Father, from whom He proceeds with and through the Son. In the West it was added that He proceeds also from the Son.
That the Divine Essence in the Second and Third Persons is derived from the First Person was understood on all hands to be a doctrine necessary to the maintenance of the Monarchia. The Nicaene faith had declared the Son to be ‘God, of God, begotten of the Father, only-begotten that is, of the essence of the Father; i.e., deriving His being from the begin of the Father by unique generation. A corresponding clause in the Constantinopolitan Creed defined the derivation of the Holy Spirit in the words ‘who proceeds from the Father’. This phrase is taken from the gospel of St. John, with a significant change of preposition which makes it analogous to ‘begotten of the Father’ in the second paragraph of the Nicene form. Thus it was explicitly taught by the Church in her symbol that the source of both the Son and the Spirit is the being of the Father, and that the sole difference between the derived persons is that the Son is from the Father by generation and the Spirit by procession. It was assumed that the procession of the Spirit, like the generation of the Son, has reference to essential life and not to mission only; the mission of the Paraclete, it was seen, rested on and arose out of His eternal dependence on the essence of the Father. Other spirits are sent by God to do His pleasure, and these too are from God, but as the work of His hands; the Spirit of God alone proceeds from God in the sense of deriving His being from the being of God.
The Son and the Spirit then have this in common that both are eternally and essentially from God. Both persons have their source in the Father, who is the one Source of Godhead. Neither person is inferior or posterior to the other; as they eternally co-exist, so they simultaneously come from from God. From these premises it would seem to follow that the eternal procession of the Spirit must be, like the eternal generation of the Son, from the Father alone; and this view was strongly held by some of the Greek theologians long before the separation of East and West. But the great majority of those who dealt with the question saw that the mediating position of the Son in the order of the divine life involved his intervention in the procession of the Spirit. On this ground the divine essence is conceived as passing eternally through the second person into the third, so that while the second derives His being immediately from the first, the third proceeds mediately, through the second. Scriptural authority for this doctrine is found in St. John 16:14, where the Spirit is said to receive of that which is the Son’s, and the Son to have all that the Father has — words which are taken to refer not only to divine prerogatives, but to divine life itself. Greek writers of the fourth century are content to say that the Holy Spirit proceeds from the Father and receives from the Son; others, or the same writers at other times, speak of Him as proceeding from the Father through the Son; or they use less guarded language, which seems to make the Son a secondary source of the Spirit. The Latins before Augustine generally follow the Greeks, without investigating the meaning of their formulas. Augustine, perceiving the obscurity in which the question was involved, gave it his attention for many years, and ultimately embodied his conclusions in a form of words which established itself in Western theology and even in Western translations of the Ecumenical Creed. The Father and the Son are (he taught) the common source of the Holy Spirit; He proceeds from both. But he proceeds from both as one source, and by one spiration. Procession from the Father involves procession from the Son, since the Father and the Son are one in substance; together with the eternal life of the Father’s essence, the Son receives also the power to communicate that essence to the Holy Spirit. Thus guarded, Augustine’s doctrine is not exposed to the charge of involving two ‘principles’ of divine life, a supposition which he explicitly rejects; and it does not differ seriously from the Greek theory of the transmission of the divine essence through the Son. But while it appealed to the Western mind, which regarded it as completing the doctrine of the Trinity, the East viewed it with growing mistrust, which became active hostility when it was discovered that the Filioque had been added to the Latin Creed. Thus to this day Augustine’s view rests only on Western authority, and cannot be regarded as an integral part of Catholic faith. The doctrine upon which the whole ancient Church was agreed is that the Holy Spirit proceeds from the Father through the Son. It is impossible not to regret that the Latin Church, if an addition to the Constantinoplitan Creed was judged to be necessary , did not add per filium rather than et filio, and make this change in concert with the Greek East….. “