For the plea will not avail them in their self-defence, that He is delivered by our Lord to His disciples third in order, and that therefore He is estranged from our ideal of Deity. Where in each case activity in working good shows no diminution or variation whatever, how unreasonable it is to suppose the numerical order to be a sign of any diminution or essential variation! It is as if a man were to see a separate flame burning on three torches (and we will suppose that the third flame is caused by that of the first being transmitted to the middle, and then kindling the end torch), and were to maintain that the heat in the first exceeded that of the others; that that next it showed a variation from it in the direction of the less; and that the third could not be called fire at all, though it burnt and shone just like fire, and did everything that fire does. But if there is really no hindrance to the third torch being fire, though it has been kindled from a previous flame, what is the philosophy of these men, who profanely think that they can slight the dignity of the Holy Spirit because He is named by the Divine lips after the Father and the Son? Certainly, if there is in our conceptions of the Substance of the Spirit anything that falls short of the Divine ideal, they do well in testifying to His not possessing glory; but if the highness of His dignity is to be perceived in every point, why do they grudge to make the confession of His glory? As if any one after describing some one as a man, were to consider it not safe to go on to say of him as well that he is reasoning, mortal, or anything else that can be predicated of a man, and so were to cancel what he had just allowed; for if he is not reasoning, he is not a man at all; but if the latter is granted, how can there be any hesitation about the conceptions already implied in “man”? So, with regard to the Spirit, if when one calls Him Divine one speaks the truth, neither when one defines Him to be worthy of honour, to be glorious, good, omnipotent, does one lie; for all such conceptions are at once admitted with the idea of Deity. So that they must accept one of two alternatives; either not to call Him Divine at all, or to refrain from subtracting from His Deity any one of those conceptions which are attributable to Deity. We must then, most surely, comprehend along with each other these two thoughts, viz. the Divine nature, and along with it a just idea, a devout intuition, of that Divine and transcendent nature.
Since, then, it has been affirmed, and truly affirmed, that the Spirit is of the Divine Essence, and since in that one word “Divine” every idea of greatness, as we have said, is involved, it follows that he who grants that Divinity has potentially granted all the rest—the gloriousness, the omnipotence, everything indicative of superiority. It is indeed a monstrous thing to refuse to confess this in the case of the Spirit; monstrous, because of the incongruity, as applied to Him, of the terms which in the list of opposites correspond to the above terms. I mean, if one does not grant gloriousness, one must grant the absence of gloriousness; if one sets aside His power, one must acquiesce in its opposite. So also with regard to honour, and goodness, and any other superiority, if they are not accepted, their opposites must be conceded.
But if all must shrink from that, as going even beyond the most revolting blasphemy, then a devout mind must accept the nobler names and conceptions of the Holy Spirit, and must pronounce concerning Him all that we have already named, that He has honour, power, glory, goodness, and everything else that inspires devotion. It must own, too, that these realities do not attach to Him in imperfection or with any limit to the quality of their brilliance, but that they correspond with their names to infinity. He is not to be regarded as possessing dignity up to a certain point, and then becoming different; but He is always such. If you begin to count behind the ages, or if you fix your gaze on the Hereafter, you will find no falling off whatever in dignity, or glory, or omnipotence, such as to constitute Him capable of increase by addition, or of diminution by subtraction. Being wholly and entirely perfect, He admits diminution in nothing. Whereinsoever, on such a supposition as theirs, He is lessened, therein He will be exposed to the inroad of ideas tending to dishonour Him. For that which is not absolutely perfect must be suspected on some one point of partaking of the opposite character. But if to entertain even the thought of this is a sign of extreme derangement of mind, it is well to confess our belief that His perfection in all that is good is altogether unlimited, uncircumscribed, in no particular diminished.
If such is the doctrine concerning Him when followed out, let the same inquiry be made concerning the Son and the Father as well. Do you not confess a perfection of glory in the case of the one as in the case of the other? I think that all who reflect will allow it. If, then, the honour of the Father is perfect, and the honour of the Son is perfect, and they have confessed as well the perfection of honour for the Holy Spirit, wherefore do these new theorists dictate to us that we are not to allow in His case an equality of honour with the Father and the Son? As for ourselves, we follow out the above considerations and find ourselves unable to think, as well as to say, that that which requires no addition for its perfection is, as compared with something else, less dignified; for when we have something wherein, owing to its faultless perfection, reason can discover no possibility of increase, I do not see either wherein it can discover any possibility of diminution. But these men, in denying the equality of honour, really lay down the comparative absence of it; and so also when they follow out further this same line of thought, by a diminution arising from comparison they divert all the conceptions that devotion has formed of the Holy Spirit; they do not own His perfection either in goodness, or omnipotence, or in any such attribute. But if they shrink from such open profanity and allow His perfection in every attribute of good, then these clever people must tell us how one perfect thing can be more perfect or less perfect than another perfect thing; for so long as the definition of perfection applies to it, that thing can not admit of a greater and a less in the matter of perfection.
Source: On the Holy Spirit (Against the Followers of Macedonius) (New Advent)