When St Gregory arrived in Constantinople in the fall of 379 he immediately addressed the question of the unity of the Father, Son, and Holy Spirit and staked out the Nicene position against his Neo-Arian opponents (Oration 20). Why does the assertion of the full divinity of the Son and Spirit not result either in three ontologically distinct beings (Arianism) or in three Gods (tritheism)? Because, answers the Theologian, the unbegotten Father is the “cause of the divinity that we recognize in the Son and Spirit” (20.6). Gregory agrees with Arius and Eunomius that the Son and Spirit originate from the Father, but he denies that this implies that they are therefore creatures, substantially dissimilar to the Father. The Father generates the eternal existence of the Son and Spirit and bestows upon them his essential reality and being. The unity of the Godhead is preserved because the Son and Spirit are referred back to the original cause, the Father, whose substance they now possess (20.7).
Nor should our argument divide them into three substances: either substances foreign to each other and wholly dissimilar, as that doctrine so aptly called “Arian madness” would have it, or substances without origin or order, which would be, so to speak, gods in rivalry. By the first of these moves, we find ourselves locked into Judaism’s narrow way of speaking, in that we define divinity simply by the notion of being unbegotten; by the second, we fall into the opposite but equal evil, supposing there are three ultimate principles and three gods, which is still more foolish than what we mentioned before. The right thing is that we should neither be such partisans of the Father that we end up canceling his Fatherhood (for whose Father would he be, if the Son’s nature is alienated from him, and made into something else, through this talk of creation?), nor such partisans of Christ that we no longer even preserve his Sonship (for whose Son would he be, if he does not look towards the Father as his cause?). Nor should we minimize the Father’s rank as ultimate cause, insofar as he is Father and begetter (for he would be the cause of minor and unworthy beings, if he were not cause of the divinity that we recognize in the Son and the Spirit). If, then, we must necessarily hold on to the one God while confessing the three hypostases, surely we must speak of three Persons, each one with its own distinctive properties. (20.6)
Gregory blocks the heresy of Arianism by insisting on the identity of substance: both the Son and Spirit are homoousios with the Father. And he blocks the heresy of tritheism by insisting on the hierarchical ordering of the three hypostases: the Son and Spirit look to the one God as the cause, originator, and governing principle of their divine existence. St Gregory can thus speak of “single, self-identical movement and will of the divine being” (20.7). The generativity of the Father gives rise to a dynamic life and motion eternally flowing from the Father and returning to him. As the Theologian famously declared in Oration 29:
Monarchy is that which we hold in honor. Yet a monarchy not limited to one person (for it is possible for the one, if at variance with itself, to become a plurality), but which consists of an equal honor of nature, a harmony of will, an identity of action, and a convergence towards the one of those that derive from it—which is impossible in the case of created nature—so that even if numerically distinct, there is no division in the essence. For this reason “from the beginning,” singularity is moved to duality and rests at trinity—and this is, for us, the Father, the Son and the Holy Spirit. (29.2–trans. John Behr)
Perhaps we might even speak of St Gregory’s doctrine of the divine processions as a timeless narrative of the divine life, a narrative grounded upon a deep correspondence with the “narrative character of the economic revelation of God” (Beeley, Gregory of Nazianzus, p. 217). Gregory is not just speculating on the immanent life of the Trinity. He is reflecting on the biblical story and penetrating to its spiritual significance.
The assertion of the monarchy of the Father inevitably leads Gregory into paradoxical language, for while the Son and Spirit indeed owe their existence to the Father, yet together they are the one Creator of the universe: the Father creates the world through the Son in the Spirit. The paradoxicality is well exhibited in St Gregory’s Farewell Oration to the bishops of the 381 Council of Constantinople:
To recount the details briefly: the One without beginning and the Beginning and the One who is with the Beginning are one God. Being without beginning is not the nature of the One without beginning, nor is being unbegotten; for nature is never a designation for what something is not, but for what something is. The affirmation of what is is not the denial of what is not. Nor is the Beginning kept separate from that which is without beginning by the fact that it is a Beginning: for being the Beginning is not his nature, any more than being the One without beginning is the nature of the other. These characteristics “surround” nature, but are not nature. And the One who is with the One without beginning and with the Beginning is not something else than what they are. The name of the One without beginning is “Father,” of the Beginning “Son,” of the One with the Beginning “Holy Spirit.” There is one nature for all three: God. The unity is the Father, from whom and towards whom everything else is referred, not so as to be mixed together in confusion, but so as to be contained, without time or will or power intervening to divide them. These three have caused us to exist in multiplicity, each of us being in constant tension with ourselves and with everything else. But for them, whose nature is simple and whose existence is the same, the principal characteristic is unity. (42.15)
Note the important statement: “The unity is the Father.”
How are the persons of the Godhead distinguished? By their hypostatic properties and causal relations: the Father is unbegotten and self-existent source of the existence of the Son and Holy Spirit; the Son is begotten by the Father; the Spirit is breathed out by the Father; both Son and Spirit have been given and eternally possess the divinity of the Father:
The Father, Son, and Holy Spirit are preserved as three unique entities because the Father is permanently “the Source who is without source—Source in the sense of cause, fount, and eternal light,” and the Son (and the Spirit) are not uncaused or without source. Because the Father eternally generates the Son and sends forth the Spirit as begotten and proceeding Divinity, they are distinct from the Father and from each other by virtue of their eternal origins in the Father. (Beeley, “Divine Causality,” 208)
Eunomius believed that it was impossible for God to communicate his indivisible essence, as it would necessarily entail division of the essence. Hence both the Son and Spirit must be dissimilar in substance and thus inferior to the Father. But St Gregory asserts the opposite. There is an ineffable way for God to generate God, without in any way compromising the divine simplicity; there is a way for the uncreated Deity to be both ingenerate and generate, uncaused and caused. In Oration 29 Gregory addresses the following question, put to him by the Heterousians: How is it, then that these [the Son and Spirit] are not co-unoriginate, if they are co-eternal with him? Gregory answers: “Because they are from, though not after him. ‘Being unoriginate’ necessarily implies ‘being eternal,’ but ‘being eternal’ does not entail ‘being unoriginate,’ so long as the Father is referred to as origin. So because they have a cause they are not unoriginate” (Or 29.3). Gregory acknowledges the superiority of the Father (“The Father is greater than I” [Jn 14:28]); but this is a superiority of cause, not of nature (Or 29.15, 30.7, 40.43). The Son and Spirit derive their existence, life, and being from the unbegotten God; they each are equal to God and are God (Or 31.9). Arian subordination is thus overcome, not by denial of the monarchy of the Father, but by the dogmatic assertion of the homoousion.
Or to put it another way, there exists a crucial difference, a difference in kind, between the divine generation that causes the trinitarian existence of God and the divine creation that brings about the existence of the world from out of nothing. The former occurs timelessly, incorporeally, incomprehensibly within the Godhead. Even if God had decided in his freedom not to create the cosmos, he would still and forever be Father, Son, and Holy Spirit, in undiminished glory. Yet in his grace and love, God the Holy Trinity did and does choose to create finite beings external to himself and thus “became” and is Creator. Though Gregory does not offer an extended treatment of divine creation as a joint act of the Trinity (such treatment would have to wait for St Gregory Nyssen), he certainly implies the unity of trinitarian agency throughout his orations. His most explicit statement comes in his Theophany homily:
“But for us there is one God, the Father, from whom are all things, and one Lord, Jesus Christ, through whom are all things” [1 Cor 8:6], and one Holy Spirit, in whom are all things, yet the “from whom” and “through whom” and “in whom” do not divide natures—for then neither would the prepositions change, nor the order of the nouns—but they characterize the properties of a nature that is one and unconfused. And this is clear from the fact that they are again brought together into one, if these other words of the same apostle are not read as an afterthought: “from whom and through whom and in whom are all things; to him be the glory unto the ages. Amen” [Rom 11:36]. The Father is a father and without origin, for he is not from anyone. The Son is a son and not without origin, for he is from the Father. But if you take it to mean an origin in time, he is also without origin; for he is Creator of time, not subject to time. The Holy Spirit is truly the Spirit sent forth from the Father, yet not as a son or through begetting but through procession, if indeed one must make some innovation in words for the sake of clarity. Nor does the Father cease to be unbegotten because he has begotten, nor does the Son cease to be begotten since he is from the unbegotten—how could that be?—nor does the Spirit change either into the Father or into the Son because he proceeds or because he is God, though to the godless this does not seem to be so; for the property does not shift. For how could it remain a property if it were shifted and changed? (Or 39.12)
For Nazianzen, therefore, the monarchy of the Father is the very heart of the trinitarian doctrine and grammar. This is difficult for Western Christians to grasp. We simply do not think much about the Father as originating cause of the Godhead, as we tend to ground the unity of the Trinity exclusively in the common essence. A comparison of the views of St Gregory with the Quicumque vult quickly reveals the difference. The generation of the Son and Spirit is mentioned in this Latin creed, but the overwhelming emphasis is on the consubstantiality of the Trinity: “What the Father is, the Son is, and the Holy Spirit is.” The divine monarchy does not function as a principle of unity. For Gregory, though, consubstantiality is a consequence of the divine monarchy. It is not an abstract principle. Monarchy and consubstantiality must be thought together. The Son and Spirit are consubstantial with the Father because they are eternally generated by him and thus perfectly share in his divinity. The person of the Father is the cause and unity of the tri-personal Godhead.
John McGuckin summarizes the importance of the divine monarchy in the theology of St Gregory:
If, in Gregory’s thought, the commonality of nature is the ground of trinitarian unity, the Father’s personal communication of his essence, entirely and without reserve, to the Son and Spirit, must be seen as the origin and principle of that unity, and the timeless initiation of those mutual relations which constitute it. This act of the Father’s self-communication specifies who the Father is; in other words, it specifies or hypostasizes the Godhead (divine ousia) as Father in the act or relation of fathering; just as the Son and Holy Spirit are specified or hypostasized in Godhead in turn by being begotten and by being sent from the Father. The Father, then, in the very particularization of himself (his individual expression of his own being) originates the very particularizations of his Son and Spirit, and thereby unfolds the whole Trinity, for the two other hypostases each concretize that being which is from him—his being and theirs—by returning that relation of generation and procession, being his Son and his Spirit respectively. (“Perceiving Light from Light in Light,” Greek Orthodox Theological Review 39 , 27)
Or as we together confess: “I believe in one God, the Father Almighty, maker of heaven and earth.”