The Nicene Creed of 325 contains an anathema that rejects anyone who claims the Son is of another ousia (essence) or hypostasis (subsistence) than the Father. At the Council of Constantinople in 381, this anathema disappears, and subsequent ecumenical documents claim there are “three perfect hypostases” in the Godhead (267). What happened between Nicaea and Constantinople? How does the same claim – there are multiple hypostases in the Trinity – shift from heresy to orthodoxy? Dragoș Andrei Giulea’s monograph proposes a new scholarly paradigm to answer these questions, focusing on the development of theological trajectories amidst fourth-century trinitarian debates. His investigation offers conceptual clarity and helpful criteria for what unifies and divides theologies in this time, ultimately nuancing earlier scholarship by scholars such as R.P.C. Hanson, Lewis Ayers, and David Gwynn.

Giulea’s thesis is twofold. First, he provides “a new map of the theological or theoretical trajectories involved in the fourth-century controversies” (12). A theological trajectory is held together by certain metaphysical assumptions about God and expressed in “a particular theological grammar grounded on a basic vocabulary” (13). Second, Giulea proposes the “pro-Nicene solution consisted of a complex synthesis of the most effective metaphysical categories of the Antiochene and Nicene theological grammars” (13), two of the proposed theological trajectories. Throughout the work, he examines these grammars by surveying the employment of and debate over key terms such as ousia and hypostasis.

After the “Introduction,” which contextualizes this work amidst the scholarly landscape, Part 1 surveys four theological trajectories from this period. The oldest trajectory is the Antiochene, which is traced back to the Council of Antioch 268. This group defines ousia as an individual substance, and thus there are multiple and degreed essences in the Godhead. Despite these ontological degrees, which imply subordinationism, this trajectory upholds the full and eternal divinity of the Son by proposing a “theology of likeness between the Son and the Father” (31). This trajectory is later seen in the Council of Antioch 341, Antioch 345, Sirmium 351, and the theologies of Eusebius of Caesarea, Basil of Ancyra, and George of Laodicea. The following chapter focuses on the Arian trajectory – here limited to Arius, Eusebius of Nicomedia, Asterius, Aetius, and Eunomius – which employs the same metaphysical assumptions of the Antiochenes, but with a low Christology. “Unlike the Antiochenes, Arius and his companions pushed the Antiochene metaphysical framework to its logical limits” (88), by sacrificing the eternality of the Son to secure the divine ousia of the Father. Giulea then turns to the “Independents,” Eusebius of Emesa and Cyril of Jerusalem, and the Homoians, namely Acacius of Caesarea and the Council in Sirmium in 357. Like the Arians, this trajectory “preserved the traditional Antiochene tenets of faith,” but unlike them, they “downplayed Antiochene metaphysical assumptions” by avoiding the terms ousia and hypostasis altogether (107). Finally, Giulea investigates the Nicene trajectory. This trajectory is not a straightforward continuation of any previous ones, but a reaction to Arianism: “the Nicene grammar gradually evolves from the early attempts of Alexander, Eustathius, and Marcellus to articulate a reaction to Arianism and defend the divine unity and the Son’s genuine divinity, to the later Trinitarian complexities devised by Athanasius, Didymus, and Apollinarius” (168). To uphold divine unity, the Nicenes defined ousia as a shared substance in distinction to an Antiochene theology of likeness.

Part 2 focuses on the development of the pro-Nicene trajectory, which overcomes the metaphysical shortcomings of the Antiochene and Nicene trajectories by fusing them. Rather than continuing his survey of various figures and councils, Giulea focuses on Basil of Caesarea as a case study for the development of the pro-Nicene trajectory. Chapter 5 frames Basil as an Antiochene who is seeking to surmount some of the latent issues in Antiochene theology in his early correspondence with Apollinarius. In this, he is “philosophically undecided, exploring, but willing to improve an older Homoiousian expression” (203). The following chapter concentrates on Contra Eunomium as a turning point in Basil’s career, in which he employs ousia in both an Antiochene and Nicene sense, though moving toward “the Nicene meaning” without modifying the Antiochene meaning of hypostasis (240). Finally, in Chapter 7, Giulea turns to Basil’s mature work, which consistently articulates a pro-Nicene grammar: “he synthesizes the Antiochene concept of ὑπόστασις, able to identify individual entities, with the Nicene concept of οὐσία, able to secure the unity of the three divine persons” (268). Giulea completes the work with a short conclusion.

There is much to commend in this monograph. First, its critical evaluation of theological “trajectories” in this period, in which several previously proposed trajectories are rejected (Heteroousianism, Anomianism, and Eusebianism), is insightful and illuminating. Second, this “new map” prevents the Athanasian slide into “Nicene” and “Arian” trajectories and centers writers such as Eusebius of Caesarea and Apollinarius as key influences on pro-Nicene theology, figures generally overlooked in earlier scholarship. There might be some concern in approaching the controversy in this way, though, especially when it comes to theological language. Not every ancient theologian focused on the terms ousia and hypostasis, especially in the early debates around Nicaea. While later writers such as Basil certainly debated these terms, one walks away with the impression that these words are the primary point of discussion all the way through – that is not typically the case in the early extant documents, especially in Eustathius and Marcellus, for example. In other words, an overemphasis on these trinitarian terms might obscure how other analogies, concepts, and frameworks might have been employed to speak of God’s oneness and threeness. This should not overshadow the creative and critical scholarship of this work, though – it is a welcome addition to the field, which nuances and reshapes our understanding of this pivotal time for the Church and Trinitarian theology.