From “On the Holy Spirit, Against the Macedonians” (ca. 380)
The Holy Spirit is, to begin with, because of qualities that are essentially holy, that which the Father, who is essentially Holy, is and such as the only begotten is, such is the Holy Spirit. Then, again, the Holy Spirit is so by virtue of life-giving, of imperishability, of invariableness, of everlastingness, of justice, of wisdom, of rectitude, of sovereignty, of goodness, of power, of capacity to give all good things, and above them all life itself, and by being everywhere, being present in each, filling the earth, residing in the heavens, shed abroad upon supernatural powers, filling all things according to the deserts of each, himself remaining full, being with all who are worthy, and yet not parted from the Holy Trinity.
He ever searches the deep things of God, ever receives from the Son, ever is being sent, and yet not separated, and being glorified, and yet he has always had glory. It is plain, indeed, that one who gives glory to another must be found himself in the possession of superabundant glory; for how could one devoid of glory glorify another? Unless a thing be itself light, how can it display the gracious gift of light? So the power to glorify could never be displayed by one who was not himself glory, and honor, and majesty, and greatness.
Now the Spirit does glorify the Father and the Son. Neither does he lie who says, “Them that glorify me I glorify” (1 Sam. 2:30); and “I have glorified you,” is said by our Lord to the Father; and again, He says, “Glorify me with the glory which I had with you before the world was.” The divine voice answers, “I have both glorified, and will glorify again.”
You see the revolving circle of the glory moving from like to like. The Son is glorified by the Spirit; the Father is glorified by the Son; again, the Son has his glory from the Father; and the Only begotten thus becomes the glory of the Spirit. For with what shall the Father be glorified, but with the true glory of the Son: and with what again shall the Son be glorified, but with the majesty of the Spirit? In like manner, again, faith completes the circle, and glorifies the Son by means of the Spirit, and the Father by means of the Son.
St. Gregory of Nyssa (ca. 335-395) was a Cappadocian bishop and theologian, a defender of Nicene orthodoxy, famed for his integration of Platonism and the allegorical exegesis of Scripture. His short treatise in defense of the full divinity of the Holy Spirit was written in response to the Macedonian, or Pneumatomachian heretics, who believed the Holy Spirit to be a lesser spiritual being. Gregory’s teaching was fully affirmed as orthodox at the Second Ecumenical Council in 381. His feast is celebrated on January 10 and March 9 on the calendars of different churches.