Much recent scholarship on Ambrose of Milan, a fourth-century bishop deeply enmeshed in the trinitarian disputes of the day, has created a dichotomy between Ambrose as a politician and Ambrose as a theologian. As Andrew Selby argues, this situation has led to an unfortunate neglect of Ambrose's De Spiritu Sancto (hereafter, DSS), inasmuch it is both deeply enmeshed in ecclesiastical politics and demonstrates skilled theological reasoning. Ambrose of Milan's On the Holy Spirit: Rhetoric, Theology, and Sources, a revision of Selby's dissertation, attempts to remedy this neglect of DSS by examining politics and theology together through the lens of classical rhetorical theory. The first part of this book presents the “quasi-judicial” situation in which Ambrose found himself. The second part of the book considers the text of DSS. In emphasizing the importance of rhetoric in Ambrose's writings, Selby contributes to recent efforts to correct the dismissal of the role of rhetoric in late antiquity.

Chapter 2 focuses on Emperor Gratian as the “judge” and the historical circumstances of the DSS. Selby argues for treating the circumstances surrounding the composition of the DSS as “quasi-judicial,” inasmuch as Ambrose is defending himself in “a courtroom fashioned by words against charges by his Homoian opponents that his faith in the divinity of the Holy Spirit is “illegal” in light of the “law” (scripture) (47). Against Jerome and many modern scholars, Selby argues that theological issues intensely mattered to the main parties in the debates. Countering recent denials of an easily recognizable “Homoian party” by Michael Stuart Williams and Peter Kaufman, Selby argues that they read into antiquity an inapplicable modern mindset that stresses the privacy of faith, pointing out the Homoians’ shared objections to using substance language and their opposition to Eunomians and Homoiousians. Selby similarly argues that theological questions mattered to Gratian because of his Roman understanding of social welfare as bound up with piety.

Continuing with this forensic approach, chapters 3 and 4 consider the Homoian “prosecution” and Ambrose, the “defendant.” Responding to the paucity of substantial studies of Homoian pneumatology, Selby provides a thorough analysis, showing that Homoians stressed the differences between the three persons in the Trinity and presented the Spirit's nature and activities as subordinate to those of the Father and the Son. The Holy Spirit does not create, but only sanctifies, pointing to the fact that the Spirit is a creature. Because the Holy Spirit is a creature, it is not worthy of worship, but assists creatures in worshipping God. Through close examination of the eight Homoian texts that are most pertinent to pneumatology, Selby points out the similarity of their pneumatology to that of Eunomius and suggests that this points to the “logical consistency” of non-Nicene pneumatology (70). This similarity helps explain Ambrose's use of Greek pro-Nicene writings in the DSS. Chapter 4 considers the impressive rhetorical, legal, and philosophical training which prepared Ambrose for arguing his case in the DSS, thus preparing for the rhetorical assessment of the texts in the remaining chapters.

The final three chapters turn to the text of DSS. Chapter 5 examines Ambrose's unclassical use of multiple exordia (prologues) and perorationes (epilogues), as well as his reliance on biblical material, attempting to show that DSS was carefully arranged with the aid of inventio (discovery of arguments). Selby's analysis of the prologues shows Ambrose's attempt to provide Gratian with a way of understanding himself through the stories of Gideon and Samson, indicating that military victory comes from believing rightly in the Holy Spirit. He also points to the way in which the prologues reinforce Ambrose's main point about the Holy Spirit's divinity, stressing the Holy Spirit's role as the true judge, over and above Gratian. Here, in accordance with classical rhetoric, Ambrose attempts to cultivate Gratian's good will and attentiveness. The epilogues focus on attacking the Arians for doing damage to the faith.

Chapter 6 examines Ambrose's use of classical rhetoric in the propositio (thesis) and reprehensio (refutation). Relying primarily on Cicero's De inventione, Selby shows how stasis theory allowed ancient orators to find the point of conflict so as to provide the most effective arguments in making their case, which makes stasis theory especially helpful in finding the points of conflict in late antique theology. Selby argues that DSS fits the definitional case type, with Ambrose arguing that the Holy Spirit, as he sets out in the propositio, is not a creature, but God. In presenting his case, Selby contends, Ambrose makes use of classical rules for arguing such a case, while using the Bible as the quasi-legal document upon which to base his argument. In the reprehensio, Ambrose focuses on the differentiae (differences) that distinguish the Holy Spirit from creatures.

Chapter 7 similarly considers Ambrose's use of stasis theory in his construction of the confirmatio (confirmation), which attributes to the Holy Spirit shared propria (properties) with the Father and the Son. Borrowing arguments from Didymus the Blind, Ambrose places particular emphasis on the Holy Spirit's participation in the activity of creation as indicating his equality with the Father and the Son. Borrowing from Basil of Caesarea's DSS, Ambrose argues, on the principle of inseparable operation, for the Spirit's divinity and fittingness for worship. In the appendix, Selby examines Ambrose's use of Greek sources, concluding that the extent of his borrowing is far less than Jerome or modern scholars would lead us to believe. Ambrose made use of his sources as was appropriate for his own rhetorical ends.

Andrew Selby does scholarship a great service by providing such a thorough examination of Ambrose's DSS. By treating the diverse facets of the work (historical, political, rhetorical, and theological), he reveals “a man whose integrity of purpose was the very characteristic that has caused him to be the object of so much reproach and renown in his own day and beyond” (283). Selby also shows the valuable insights that can be gained by examining late antique Christian theological works through the lens of ancient rhetoric. Finally, he demonstrates the same rhetorical excellence which he highlights in Ambrose's work, as his study is well-organized, clearly written, and pleasing to read.