Demonstration of the Spirit and of power : rhetoric and Ambrose of Milan’s On the Holy Spirit.

Despite being the first extended defense of the divinity of the Holy Spirit written in Latin and influencing the Trinitarian theology of Augustine of Hippo, Ambrose of Milan’s On the Holy Spirit (De Spiritu Sancto) has received little scholarly attention. This attention has been unduly influenced by Jerome’s criticism of the work, in which he claimed that De Spiritu Sancto (DSS) was poorly written and largely plagiarized from Greek writings. This dissertation seeks to change this perspective by claiming that Ambrose defines the Holy Spirit in a way consistent with pro-Nicene theology using classical Ciceronian rhetoric to interpret Scripture in a quasi-judicial situation: Emperor Gratian played the role of judge, the Homoians served as the prosecution, and Ambrose was the defendant. Instead of viewing Ambrose’s DSS through the lens of source-criticism, this study utilizes classical rhetorical theory, especially stasis theory, as a methodology that gives due weight to the conflict in which Ambrose was embroiled as well as the bishop’s internal theological reasoning. Stasis theory provided students of rhetoric a means to generate arguments particularly relevant for the case before them. After documenting the ecclesiastical-political conflict that occasioned DSS’s composition, this study provides the first comprehensive account of the pneumatology of Ambrose’s opponents, the Latin Homoians. Ambrose’s own intellectual formation is then investigated, revealing his intimate knowledge of rhetoric and his acquaintance with some philosophical doctrines, both of which factored into the genesis of DSS. The prologues and epilogues of DSS reveal Ambrose’s attention to the concerns—theological and political—of his primary audience, the Emperor Gratian. Finally, his rhetorically conditioned argumentative strategies against the Homoians and for a pro-Nicene doctrine of the Holy Spirit are explained. Ambrose used the “Definition Issue” in stasis theory to understand the Holy Spirit’s identity, interpreting Holy Scripture to discover his differentiae from creatures but also his shared propria with the Father and the Son. Not only does this dissertation provide the first full study of Ambrose’s DSS, but it also suggests that rhetorical theory significantly influenced argumentation in fourth-century Trinitarian controversies, though this has been overlooked in modern scholarship