Karl Barth Church Dogmatics 1/1 The Doctrine of the Word of God p. 468f

1. εἰς τὸ πνεῦμα τὸ ἅγιον, τὸ κύριον
2. τὸ ζωοποιοῦν
3. τὸ ἐκ τοῦ πατρὸς ἐκπορευόμεν
4. τὸ σὺν πατρὶ καὶ υἱῷ συν προσκυνουμενον καὶ  συνδοξαζόμενον 
1. in Spiritim sabctum Dominum
2. et vivificantem
3. qui ex Patre et Filioque procedit
4. quie cum Patre et Filio simul adoratur at conglorificatur

Church Dogmatics 1.1

1. We believe in the Holy Ghost, the Lord. The underlying Greek text uses κύριον adjectively here. This implies no limitation of the statement as we have it in the Latin Dominus and English “Lord.” Like the Father and the Son, the Spirit is not Dominus, Lord, as one Lord side by side with two others. He is Lord in inseparable unity with the Father as Lord and the Son as Lord. Our first point with a backward glance at the ἔνα κύριον of the second article, is that the Holy Spirit, with the Father and the Son, is the bearer of the lordship of God which is not based on any higher lordship. With the Father and the Son He is the one sovereign divine Subject, the Subject who is not placed under the control or inspection of any other, who derives His being and existence from Himself. But the adjectival use of κύριος along with a fact we have not yet taken into account, and which is not evident in Latin (or German), namely the πνεῦμα itself is a neuter, forces us to note at once the special way in which the Holy Spirit is all this. These two circumstances indicate that He is it all in a neutral way, neutral in the sense of distinct, i.e. distinct from the Father and the Son whose modes of being are reciprocal, but neuter in the sense of related, i.e. related to the Father and the Son, whose reciprocity is not a being against, but a being to and from and with one another. This togetherness or communion of the Father and the Son is the Holy Spirit. The specific element in the divine mode of being of the Holy Spirit thus consists, paradoxically enough, in the fact that he is the common factor in the mode of being of God the Father and that of God the Son. He is what is common to them, not in so far as they are the one God, but in so far as they are the Father and the Son.

Spiritus sanctus commune aliquid est Patris et Filii (Augustine, de Trin., 6.5, 7). He stands “in the middle between the Begotten and Unbegotten” (John of Damascus., Ekdos., 1.13). Nomen Spiritus sancti non est alienum a Patre et Filio, quia uterque est et spiritus et sanctus (Anselm of Canterbury,  Ep de incarn., 2)

Thus even if the Father and the Son might be called “person” (in the modern sense of the term), the Holy Spirit could not possibly be regarded as the third “person.” In a particular way the Holy Spirit is what the Father and Son also are. He is not a third spiritual Subject, a third I, a third Lord side by side with two others. He a third mode of being of the one divine Subject or Lord.

In this regard it is worth noting that the Church has forbidden the portrayal of the Holy Ghost in human form (Bartmann, Lehrb. d. Dogm.7  Vol. 1, 1928, p. 194).

He is the common element, or, better, the fellowship, the act of communion, of the Father and the Son. He is the act in which the Father is the Father of the Son or the Speaker of the Word and the Son is the Son of the Father of the Word of the Speaker.

He is communio quaedam consubstantialis (Augustine, De trin., 15.27, 50) He is the vinculum pacis (Eph. 4.3), the amor, the caritas, the mutual donum between the Father and the Son, as it has often been put in the train of Augustine. He is thus love in which God (loves Himself, i.e. loves Himself as the Father and as the Son, and) as the Father loves the Son and as the Son loves the Father. Si charitis qua Pater diligi Filius, ineffabiliter communionem demonstral amborum, quid convenientus quam ut ille dicatur charitas proprie, qui Spiritus est communis ambobus (Augustine, De trin., 15.19, 37). To this extent—the figurative nature of the expression does not need to be emphasised—He is the “result” of their common “breathing,” spiratio Amborum sacrum spiramen, nexus amorque, as we read in Kyrie-Tropus “ Cuncti potens”  (L. Eisenhofer, Handb. der  kath, Liturgih, Vol 2, 1933, p. 89).

How far is this act to be understood as a special divine mode of being? It is obviously to be regarded as a special divine mode of being because this common being and work of the Father and the Son is special and distinct mode of divine being as compared to that of the Father and the Son. It is obviously to be understood as a divine mode of being because in this act of His divine being as Father and Son, in the reciprocal love of His, God cannot be or do anything other or less than what is equal to Himself. There cannot be any higher principle from which and in which the Father and the Son must first find themselves together. They can find themselves together only in their own principle. But this principle is the breathing of the Holy Spirit or the Holy Spirit Himself. Again the work of this love is not the created world; it is the reciprocal love of the Father and the Son. The work then, must be what is equal to them, and this equal is the Holy Spirit.

Father and Son are non participatione, sed essentia  sua, neque superioris alicuius, sed suo proprio servantes unitatem Spiritus in vinculo pacis (Augustine De trin 6.5, 7). Nam ideo amor non est impar tibi aut Filio tuo, quia tantuni amas te et illum et ille te et seipsum, quantus es tu et ille, nec est aliud a te et ab illo (Anselm of Canterbury, Prosl., 23). Si nulla umquam creatura, id est si nihil amquam aladiud esset quam summus spiritus Pater et Filius: nihilominus seipsos et invicem Pater et Filius diligerent.Consequitir itaque hunc amorem son esse aliud quam quod est Pater et Filius, quod est summa essentia (Mono., 53i).

Thus God—and to this degree He is God the Holy Spirit—”antecedently in Himself” the act of communion, the act of impartation, love, gift. For this reason and in this way and on this basis He is so in His revelation. Not vice versa! We know Him thus in His revelation. But He is not this because He is it in His revelation; because He is it antecedently in Himself, He is it also in His revelation.

He is in His revelation the donator doni because in Himself, as the Spirit of the Father and the Son, He is the donum donartoris (Augustine, De trin., 5.11) Donum vere dicitur non ex eo tantum, quod donetur, sed ex proprietate, quam habuit ab aeterno. Unde et ab aeterno fuit donum. Sempiterne enim donum fuit, non quai daretur, sed quia processit a Patre et Filio . . . temporaliter autem donatum est (Peter Lombard, Sent., I, dist. 18D). Donum non dicitur ex eo quod actu datur sed in quantum habet aptitudinem ut possit dari. Unde ab aeterno divina persona dicitur donum, licet ex tempore detur (Thomas Aquina, S. th.qu. 38, art I and 4). Amor habet rationem primi doni, per quod omnia dona gratuita donatur. Unde com Spiritus sanctus procedat ut amor . . .  procedit in ratione doni primi (ib., art. 2C).

The Holy Spirit says the dogma with its τὸ κύριον is the Lord who acts on us in revelation as the Redeemer, who really sets us free and really makes us the children of God, who really gives His Church the words to speak God’s Word, because in this work of His on us He simply does in time what He does eternally in God because His mode of being of the hidden essence of God, so that it really is the hidden essence of God Himself, and therefore the Lord in the most unrestricted sense of the term, who, in all His inscrutability, is revealed in revelation in this respect too.