Against those who assert that it is not proper for “with whom” to be said of the Son, and that the proper phrase is “through whom.”
16. But their contention is that to use the phrase “with him” is altogether strange and unusual, while “through him” is at once most familiar in Holy Scripture, and very common in the language of the brotherhood. What is our answer to this? We say, Blessed are the ears that have not heard you and the hearts that have been kept from the wounds of your words. To you, on the other hand, who are lovers of Christ, I say that the Church recognizes both uses, and deprecates neither as subversive of the other. For whenever we are contemplating the majesty of the nature of the Only Begotten, and the excellence of His dignity, we bear witness that the glory is with the Father; while on the other hand, whenever we bethink us of His bestowal on us of good gifts, and of our access to, and admission into, the household of God, we confess that this grace is effected for us through Him and by Him.
It follows that the one phrase “with whom” is the proper one to be used in the ascription of glory, while the other, “through whom,” is specially appropriate in giving of thanks. It is also quite untrue to allege that the phrase “with whom” is unfamiliar in the usage of the devout. All those whose soundness of character leads them to hold the dignity of antiquity to be more honourable than mere new-fangled novelty, and who have preserved the tradition of their fathers unadulterated, alike in town and in country, have employed this phrase. It is, on the contrary, they who are surfeited with the familiar and the customary, and arrogantly assail the old as stale, who welcome innovation, just as in dress your lovers of display always prefer some utter novelty to what is generally worn. So you may even still see that the language of country folk preserves the ancient fashion, while of these, our cunning experts in logomachy, the language bears the brand of the new philosophy.
What our fathers said, the same say we, that the glory of the Father and of the Son is common; wherefore we offer the doxology to the Father with the Son. But we do not rest only on the fact that such is the tradition of the Fathers; for they too followed the sense of Scripture, and started from the evidence which, a few sentences back, I deduced from Scripture and laid before you. For “the brightness” is always thought of with “the glory,” “the image” with the archetype, and the Son always and everywhere together with the Father; nor does even the close connection of the names, much less the nature of the things, admit of separation.
Source: De Spiritu Sancto (New Advent)