Despite its lengthy gestation period of approximately twenty years, Augustine’s De Trinitate was, according to its author, always intended to be read as one sustained, coherent inquiry into the heart of Christian faith. Many interpreters have failed to perceive the unity Augustine claims for his treatise, but according to Dom Gioia’s proposal, this is largely because, too often, interpreters have remained fixated on its structure and sequential arrangement and neglectful of its focus on theological epistemology. Such a thesis could be read as importing modern philosophical concerns into the De Trinitate, but Gioia heads off this worry by avowing, “Augustine does not embark on an explicit reflection on the conditions of knowledge of God, but aims at introducing his reader into the practice of this knowledge and then, only retrospectively, determines its conditions not critically but theologically or, rather, from a theologically ruled critical point of view” (p. 3). On this reading, the coherence of the De Trinitate is explained by holding questions about the Triune divine identity together with questions about how human beings come to know or participate in that identity. The answer to these two sets of questions, Gioia suggests, lies in viewing the former set as the explanation for the latter: “The Trinitarian identity of God is the only way to explain how we come to know him” (p. 3).

Gioia’s primary sparring partner is Olivier Du Roy’s 1966 monograph on the formation of Augustine’s Trinitarian theology, L’intelligence de la foi en la Trinité selon S. Augustin (Paris: Etudes Augustiniennes). For Du Roy, what Augustine believes about the Trinity remains independent from faith. Knowledge of God comes by way of an assumption that Plotinian hypostases are identical with the Christian Trinity. When that “anagogical” knowledge is frustrated by the vicissitudes of human weakness, however, only then does Augustine turn to the economy of salvation, invoking the incarnation as a kind of complementary way of knowing God and, thus, divorcing theological epistemology from the Christian narrative of salvation. In contrast to this picture, Gioia’s Augustine speaks with a Barthian accent of the Father, who, being invisible and immutable, reveals himself by way of Christ and the Holy Spirit. On this account, theological epistemology is a subset of soteriology (pp. 23, 107–17, 146)—or, more precisely, coincides with soteriology. If Du Roy’s Augustine finds human capacity insufficient for divine knowledge and is thereby driven back to the economy, Gioia shows an Augustine able to conceive of human insufficiency only retrospectively from the economy: “Only from the viewpoint gained by reconciliation and salvation are we able to discover the radical dependence of our being on God” (p. 23; cf. pp. 66–67).

In the early chapters of his monograph, Gioia highlights, primarily by way of a close reading of Augustine’s Book 4, the convergence between the doctrine of the Trinity and human knowledge of God precisely in the coincidence or identity between the divinely effected reconciliation between God and humanity and the revelation of the Father through Christ and the Spirit (pp. 32–34). Chapter 3 considers Augustine’s relationship to Platonic philosophy, concluding that it is employed largely for its ethical benefits, as a way of elucidating “the identification of God’s image in us, with a view to its reformation” (p. 64).

Chapter 4 examines Augustine’s Christology in this light. It deepens an appreciation for how Augustine will invoke Platonic categories only if they are chastened by according theological primacy to the economy as it is delineated in Scripture. Here Gioia takes aim at a common criticism of Augustine’s “psychological model” of the Trinity, namely, that it tends to take the “givens” of the construction of individual humans as reflective simpliciter of God’s Triune life. Gioia argues cogently that, on the contrary, “Our image of God does not simply consist in the fact that we are memory, knowledge, and love, but in the fact that God becomes the object of our memory, knowledge, and love—something possible only thanks to his self-manifestation and self-giving in Christ and the Holy Spirit” (pp. 82–83).

Gioia’s chapters 5 and 7 mark the transition from Augustine’s consideration of the Trinitarian “missions” in the economy (Books 1–7) to what those missions reveal about the inner-life of God, or, in modern terms, the “immanent Trinity.” Here the concern is—again with echoes of Barth—to guard the freedom of God so that “God remains unknowable even in his self-revelation” (pp. 116, 149). As “God from God,” the Son truly reveals the Father since our apprehension of him as such is dependent on his eternal relation of filiation to the Father (p. 119). The highly technical nature of Books 5–7 is best seen as owing its form and idiom to its polemical context, rather than as seeking to subsume what can be discerned of God’s Trinitarian life in the economy to an overarching ontological framework (pp. 158–61).

Having thus described the essential identity between reconciliation and revelation, in later chapters Gioia turns explicitly to the issue of human knowledge and posits an inextricable link between the bent of the human will and knowledge. Neutrality is not an option, and any space for knowledge not already formed by love is thus eliminated (pp. 213, 218). Augustine “challenges the very possibility of philosophizing without Christ” (p. 219). This insight is then worked out in Gioia’s chapter 11 with a delimiting focus on anthropology. Here Gioia presses the point that human psychology is made a vehicle for understanding the Triune life not because of its intrinsic suitability for that purpose, as if the point were simply our “similarity with God” or innate “capacity” (p. 288), but rather as a means to explore our dynamic participation in God’s salvation (pp. 293–94).

Because of its thoroughness (no relevant piece of secondary literature is left unmentioned), elegance (marred only by a large number of typos in the book’s final chapters), and lucid arrangement of its themes (mostly following the order of the De Trinitate itself), Gioia’s book will surely take its place among the growing number of sophisticated responses to the twentieth-century backlash against Augustine’s alleged misunderstanding of patristic (especially the Cappadocians’) Trinitarian theology. Along with the work of Rowan Williams, Michel René Barnes, Lewis Ayres, and others, Gioia’s book will go a long way towards demonstrating that Augustine, far from being a liability in engagement with fourth-century Nicene theology as well as the continuing development of contemporary Trinitarian theology, remains indispensable for any serious inquiry into the dogmatic and devotional heart of Christian teaching.

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