Few writers provide as many different windows through which to observe the twelfth century's literate culture than John of Salisbury (1115/20-1180). He meticulously detailed his education and the men who taught him in his Metalogicon, and he compiled a correspondence of 325 letters to some of the most important figures of the period. In his lengthy treatise Policraticus, he set forth a model for the body politic that still attracts attention from political theorists, and in this respect is rather unique among thinkers of the Central Middle Ages. Add to this his forays into history and hagiography, and he offers historians a magnificent snapshot of the things that clerical elites liked to think about.
Historians have seen John variously as a "humanist," a critic of "courtly culture," a compiler of classical ideas, a representative of the so-called "Renaissance of the Twelfth Century," and an exemplary intellectual in politics (albeit a somewhat tragic figure in this regard). In Irene O'Daly's engaging new study, John represents the "Roman Renaissance," an innovative application of Roman philosophical ideas--especially Stoic ones derived from Seneca and certain works of Cicero--to contemporary political problems. O'Daly argues that scholars like Cary Nederman who have emphasized John's "Aristotelianism" have neglected the Roman-ness of his approach to the political order. This is important, because those Roman ideas allowed John to develop "a sophisticated theory of political duties, emphasizing solidarity and moral obligation within the community" (9). Thus John's work, and particularlyPolicraticus, "marks an important milestone in the development of medieval communitarian thought" (8).
O'Daly brings considerable technical skill to her endeavor. She confronts difficult questions regarding the transmission and reception of classical texts in John's work (drawing on the pioneering work of Janet Martin and others), and has carefully read the annotations to key manuscripts of the Policraticus as well as what may be John's own notes on a copy of Lactantius's Institutiones divinae. Throughout the book, her method, following "Cambridge School" historian Quentin Skinner, seeks to place John firmly in the intellectual context of the twelfth century.
Having laid out a standard chronology of John's life and works in her introduction, O'Daly proceeds thematically. She devotes six chapters to the ways in which John used the Roman inheritance to create a political morality for a twelfth-century prince, here presented as a ruler of a political community devoted to the common good. In the opening chapter, O'Daly subtly surveys the classical tradition as John would have accessed it, carefully noting that twelfth-century students approached classical works in ways that may be irrecoverable to modern historians. What, for example, could "Stoicism" mean to someone who knew it only through a selection of works by Seneca and Cicero? The classical tradition was unstable and in flux, and so could not act as a clearly defined source for ideas. Moving beyond past scholarly emphases on the aesthetic appeal or allegorical utility of these texts, O'Daly argues that "John viewed the residual heritage of ancient Rome instrumentally, seeking whatever moral lessons it could offer" (27). To show how he encountered this heritage, she skillfully surveys the sources that John mined, along with the various manuscripts and institutional contexts in which he could have found them. Students of the reception of Cicero and Seneca in the Middle Ages will be most grateful for the clear summaries of those topics in this chapter
In chapters 2 and 3, O'Daly turns to the key concerns of Roman philosophy, and especially of the Stoics: nature and reason, and one's duties in a body politic. While the Stoics had paid special attention to living secundum naturam, John of Salisbury Christianized this concept, presenting nature as an imitation of God (thus avoiding pantheistic implications of Stoicism). In constructing an ethical framework for the good life, "John elides 'living in accordance with nature' with 'living in accordance with God's purpose in the world'" (84). But the Christian operates within a political order, and thus God's purpose was experienced in public life, so O'Daly elegantly shifts her focus to John's "cooperative model of the polity" (92). Again, she carefully demonstrates how John read classical sources, especially Cicero's De officiis, through the lens of current Christian concepts like caritas, to create a political ethics based on reciprocal obligation
In another graceful segue, O'Daly shows in chapter 4 how this cooperative model informs the metaphor at the heart of Policraticus, that of the body politic with the prince at its head. Although she indicates some discomfort with the traditional view that John invented the supposedly Plutarchan Institutio Trajani that he claimed to be its source, she does not explore this problem as deeply as one might expect. What she does provide is a wonderfully thorough summary of John's other possible sources for the metaphor, both classical and medieval, as well as how other twelfth-century writers employed it. While many past commentators have argued that John used the metaphor simply to describe the social order he saw around him, O'Daly sees it as a way to integrate the linked notions of nature, duty and cooperation: "The body, a confined system, serves to illustrate the necessary interdependence of the members of the polity who are engaged in pursuing the public good, the health of the body politic" (135)
What is key about the Roman Renaissance, then, is that it allowed John of Salisbury to create a model for leadership in his twelfth-century context. In chapter five, O'Daly argues that John drew on the Stoic ideal of moderation to outline the attributes of virtuous secular and ecclesiastical leaders. Political life was necessarily a life of moderation that rejected the "courtly" pleasures of hunting, gaming, and drinking. Here she insists again that John's influences are largely Stoic, and she rejects Nederman's identification of John's view of moderation with the Aristotelian "mean." She brings the discussion into the realm of practical politics by analyzing annotations in what seems to have been John's copy of Lactantius's Institutiones divinae--including audi Thoma ("listen, Thomas")--as direct instructions to Archbishop Thomas Becket on how to comport himself in public life (169).
The sixth and final chapter outlines John's views on "the princely head," including this supposed legitimation of tyrannicide. Again, O'Daly successfully demonstrates how John Christianized his Roman sources in a highly original fashion, identifying the Stoic "law of nature" with the "law of God" (186). The prince's obligation to rule according to this law inevitably places constraints on his behavior and requires moderation. Those who transgress these constraints are tyrants, who in some cases (as shown by ancient and biblical history) may be killed. However, the populace is also bound by the principle of moderation, which makes tyranicide less a political necessity than a warning (184). Returning to the practical implications of John's work, O'Daly looks at how John presented three twelfth-century leaders: the tyrant Stephen of England, the schismatic Frederick I Barbarossa, and the martyr Thomas Becket. In all these cases, she finds that John channeled ethical advice from the Roman Stoics into his analysis of contemporary politics.
O'Daly persuasively demonstrates that John of Salisbury deployed Roman ideals to create an ethical basis of princely rule, and she succeeds in surrounding John with a rich and dynamic intellectual context derived in part from the Stoics. As for her polemic against Nederman's views on John's Aristotelianism, I am willing to regard the two approaches as complementary. It is not clear to me that the classical tradition, as experienced by thinkers like John of Salisbury, was compartmentalized into Stoic and Aristotelian streams in a meaningful way, and classical influence is certainly not a zero-sum game. There seems to be little reason to preclude the possibility that John and his contemporaries had a real encounter with Aristotle that has not left a clear trail for modern investigators to follow. Indeed, O'Daly's careful unearthing of John's influences, which came to him through sometimes surprising channels, offers some support to Nederman's contention that classical ideas (such as Aristotelian ethics) reached twelfth-century writers through an "underground tradition of learning" (quoted by O'Daly, 153); her approach in fact seems to me to epitomize Nederman's call for "a more sensitive approach to the treatment of the dissemination of ideas during the Middle Ages." 
There are a few trends in recent scholarship with which this book does not engage, and these would seem to present fruitful avenues for future research. The first, and perhaps most important, is the scholarship on "courtly culture," in which John appears as a critic of the new political dynamics. Joachim Bumke, Reto Bezzola, Egbert Türk, and others have looked carefully at how literature and ethics interacted with court power in the same contexts that O'Daly approaches, and this sort of approach could help illuminate what was at stake in John of Salisbury's political ethics. In addition, the period after the Fathers and before 1100 is something of a blank space in her analysis, so there is certainly room for a study of the "Roman Renaissance" that revisits questions of change and continuity. It is surprising (but perhaps in some ways a relief) that this book does not really explore that basic notion of "renaissance" and its historiography, for it implicitly engages with the theses of Erwin Panofsky's seminal Renaissance and Renascences in Western Art, among other classic texts.  Finally, given her emphasis on moderation and proper behavior, O'Daly potentially points a way to connect all this with the history of manners, as outlined most impressively in Jaeger's The Envy of Angels.  I offer these suggestions in the hope that future work will pursue these connections on the very solid foundation that O'Daly has laid.
To conclude, students and scholars in other specialties will find in this book a clear and helpful introduction to John's ethical and political thought, and also to the diffusion of Roman ideas in the twelfth century. Not only that, but experienced scholars will be provoked to rethink assumptions about how received traditions subtly worked their way through medieval schools, manuscripts, and minds.
1. Cary J. Nederman, "Nature, Ethics, and the Doctrine of 'Habitus': Aristotelian Moral Psychology in the Twelfth Century," Traditio45 (1990): 87-110, here at 109.
2. Erwin Panofsky, Renaissance and Renascences in Medieval Art (1960, reprint New York: Routledge, 2018).
3. C. Stephen Jaeger, The Envy of Angels: Cathedral School Culture and Social Ideals in Medieval Europe, 950-1200 (Philadelphia: University of Pennsylvania Press, 1984).