VIII. Confess, my friends, the Trinity to be of One Godhead; or if you will, of One Nature; and we will pray the Spirit to give you this word God. He will give it to you, I well know, inasmuch as He has already granted you the first portion and the second; and especially if that about which we are contending is some spiritual cowardice, and not the devil's objection. Yet more clearly and concisely, let me say, do not you call us to account for our loftier word (for envy has nothing to do with this ascent), and we will not find fault with what you have been able to attain, until by another road you are brought up to the same resting place. For we are not seeking victory, but to gain brethren, by whose separation from us we are torn. This we concede to you in whom we do find something of vital truth, who are sound as to the Son. We admire your life, but we do not altogether approve your doctrine. You who have the things of the Spirit, receive Himself in addition, that you may not only strive, but strive lawfully, which is the condition of your crown. May this reward of your conversation be granted you, that you may confess the Spirit perfectly and proclaim with us, aye and before us, all that is His due. Yes, and I will venture even more on your behalf; I will even utter the Apostle's wish. So much do I cling to you, and so much do I revere your array, and the colour of your continence, and those sacred assemblies, and the august Virginity, and purification, and the Psalmody that lasts all night and your love of the poor, and of the brethren, and of strangers, that I could consent to be Anathema from Christ, and even to suffer something as one condemned, if only you might stand beside us, and we might glorify the Trinity together. For of the others why should I speak, seeing they are clearly dead (and it is the part of Christ alone to raise them, Who quickens the dead by His own Power), and are unhappily separated in place as they are bound together by their doctrine; and who quarrel among themselves as much as a pair of squinting eyes in looking at the same object, and differ with one another, not in sight but in position— if indeed we may charge them only with squinting, and not with utter blindness. And now that I have to some extent laid down your position, come, let us return again to the subject of the Spirit, and I think you will follow me now.
IX. The Holy Ghost, then, always existed, and exists, and always will exist. He neither had a beginning, nor will He have an end; but He was everlastingly ranged with and numbered with the Father and the Son. For it was not ever fitting that either the Son should be wanting to the Father, or the Spirit to the Son. For then Deity would be shorn of Its Glory in its greatest respect, for It would seem to have arrived at the consummation of perfection as if by an afterthought. Therefore He was ever being partaken, but not partaking; perfecting, not being perfected; sanctifying, not being sanctified; deifying, not being deified; Himself ever the same with Himself, and with Those with Whom He is ranged; invisible, eternal, incomprehensible, unchangeable, without quality, without quantity, without form, impalpable, self-moving, eternally moving, with free-will, self-powerful, All-powerful (even though all that is of the Spirit is referable to the First Cause, just as is all that is of the Only-begotten); Life and Lifegiver; Light and Lightgiver; absolute Good, and Spring of Goodness; the Right, the Princely Spirit; the Lord, the Sender, the Separator; Builder of His own Temple; leading, working as He wills; distributing His own Gifts; the Spirit of Adoption, of Truth, of Wisdom, of Understanding, of Knowledge, of Godliness, of Counsel, of Fear (which are ascribed to Him) by Whom the Father is known and the Son is glorified; and by Whom alone He is known; one class, one service, worship, power, perfection, sanctification. Why make a long discourse of it? All that the Father has the Son has also, except the being Unbegotten; and all that the Son has the Spirit has also, except the Generation. And these two matters do not divide the Substance, as I understand it, but rather are divisions within the Substance.
X. Are you labouring to bring forth objections? Well, so am I to get on with my discourse. Honour the Day of the Spirit; restrain your tongue if you can a little. It is the time to speak of other tongues— reverence them or fear them, when you see that they are of fire. Today let us teach dogmatically; tomorrow we may discuss. Today let us keep the feast; tomorrow will be time enough to behave ourselves unseemly— the first mystically, the second theatrically; the one in the Churches, the other in the marketplace; the one among the sober, the other among the drunken; the one as befits those who vehemently desire, the other, as among those who make a joke of the Spirit. Having then put an end to the element that is foreign to us, let us now thoroughly furnish our own friends.
XI. He wrought first in the heavenly and angelic powers, and such as are first after God and around God. For from no other source flows their perfection and their brightness, and the difficulty or impossibility of moving them to sin, but from the Holy Ghost. And next, in the Patriarchs and Prophets, of whom the former saw Visions of God, or knew Him, and the latter also foreknew the future, having their master part moulded by the Spirit, and being associated with events that were yet future as if present, for such is the power of the Spirit. And next in the Disciples of Christ (for I omit to mention Christ Himself, in Whom He dwelt, not as energizing, but as accompanying His Equal), and that in three ways, as they were able to receive Him, and on three occasions; before Christ was glorified by the Passion, and after He was glorified by the Resurrection; and after His Ascension, or Restoration, or whatever we ought to call it, to Heaven. Now the first of these manifests Him— the healing of the sick and casting out of evil spirits, which could not be apart from the Spirit; and so does that breathing upon them after the Resurrection, which was clearly a divine inspiration; and so too the present distribution of the fiery tongues, which we are now commemorating. But the first manifested Him indistinctly, the second more expressly, this present one more perfectly, since He is no longer present only in energy, but as we may say, substantially, associating with us, and dwelling in us. For it was fitting that as the Son had lived with us in bodily form— so the Spirit too should appear in bodily form; and that after Christ had returned to His own place, He should have come down to us— Coming because He is the Lord; Sent, because He is not a rival God. For such words no less manifest the Unanimity than they mark the separate Individuality.
Source: Orations (New Advent)