Though Vacarius was born in Lombardy and studied in Bologna, the center of legal studies in twelfth-century Europe, he spent his entire career in England. In the mid-1140s he entered the service of Archbishop Theobald of Canterbury, moving in 1159 to the household of Roger, Archbishop of York, until the latter's death in 1181, and remaining under Geoffrey Plantagenet until his own death in about 1200. At some point he received priestly ordination and acted as papal judge delegate on seven occasions. In addition to bureaucratic duties, he introduced the teaching of Justinianic Roman law in England, very likely at Oxford, and participated in the theological controversies of his day. Jason Taliadoros, who focused his doctoral studies at the University of Melbourne on Vacarius, notes the challenge posed by the Italian jurist's multidisciplinarity: “It is perhaps the difficulty of following Vacarius into these various areas of interest, namely Roman law, canon law, theology, exegesis, logic, and philosophy, that has prevented any single, comprehensive study on this man and his intellectual output” (1). Taliadoros argues for a re-evaluation of Vacarius, arguing that his “contribution to twelfth-century debates on legal and theological” issues “represents a unique approach, informed by a practical and pastorally oriented scholasticism” (291).

Vacarius's works reveal four strands to his thought: “teaching law, marriage, christology, and sacramental issues” (1), which are analyzed in successive chapters. The Liber pauperum, his most noted writing, was the first legal manual in England, “an organic and developing textbook designed to fit the needs of its students, and accommodate their increasing understanding of both Justinianic Roman law in particular, and legal procedure generally” (35). Intended for both Roman and canon lawyers, the ius commune community, it did not simply mix but rather integrated the two. It seems that this work, which epitomized Justinian's Digest and Code, was not studied in its own right but served as a useful companion to the study of canon law. “This need for practicality, occasioned by the flood of papal decretals to England… . demanded the adoption of principles of procedure and the like for the equitable application of the canons of the Decretum in everyday cases” (52–53).

Just as Vacarius sought universality in the teaching of the ius commune, he attempted in a similar way to apply such law to marriage, which spanned both law and theology. In the Summa de matrimonio, he analyzed the two competing marriage-formation theories: the consummation model of Gratian and Rufinus and the consensual model of Peter Lombard, criticizing both on several grounds. He proposed the notion of traditio (the “delivery” or mutual self-giving of the partners) as “the legal moment that crystallized the formation of a marriage between spouses” (126). He sees it closely linked with consent, the affectio maritalis, as heuristic device, not as an alternative solution. “Further, for Vacaiius, this debate is not a sterile, academic one; instead it is based on the realities present in the twelfth century: separation, divorce, concubinage, and the clandestine marriages of young girls… . Thus marriage confronts Vacarius as both a functionary and a litteratus, that is, on a practical as well as on an intellectual level.” He offers “a synthesis that transcends law, to encompass theology and sacramental matters” (129–130).

The theological debates of the twelfth century focused to a large extent on the hypostatic union, the doctrine that Christ was both God and man. The early councils of the Church had solemnly defined that Christ was one person in two natures, the human and the divine. How, then, does one explain theologically this unity and duality in Christ? While Vacarius discussed the question in two short works, his position does not seem to have been comprehensively evaluated previously. The longest and most challenging chapter of the book under review attempts to remedy the neglect. Suffice it to say that the author “broadly speaking” identifies Vacarius's assumpto homo position with that “posited by Hugh of St. Victor and others,” but which “does not slavishly adhere to or mimic Hugh's Christology.” His approach is methodologically quite distinct “with its recourse to sophisticated theological language, ranging from definitions of nature, substance, and person, to speculative grammar, and to philosophical notions of change derived from Aristotle's categories” not utilized up to that time. On the other hand, Vacarius's works “lack the polish, the precise application and citation of authorities, and the systematic comprehensiveness of a Gilbert of Poitiers or a Robert of Melun; nevertheless they contain an element of practical pastoral immediacy” (211–212).

The final chapter treats the Liber contra multiplices et varios errors that was in refutation of Hugh Speroni of Piacenza, who had studied law with Vacarius. These errors concerned the sacraments (holy orders, the Eucharist, penance, and baptism) and the theological concepts of Original Sin, justification, works, and ecclesiology. Speroni maintained a strong position on predestination and the uselessness of good works; he also rejected the value of ministrations performed by unworthy priests. Vacarius here once again “applies the lawyer's rigorous dialectic and forensic examination of argument, but with a sensitivity to, and a deep knowledge of, both theology and exegesis” (288).

Taliadoros acknowledges that the works of Vacarius have traditionally been seen “by scholars as having little worth in the wider understanding of medieval law and theology.” He hopes to have demonstrated that the unique perspective of Vacarius was heuristic, rather than doctrinal, resolving problems in theology or sacramentology “by the universal application of legal science,” motivated by a concern for practical pastoral needs (294). I suspect that this contribution will not be sufficient to promote Vacarius from his accustomed minor ranking. The bibliography, however, is truly exceptional. Among its primary sources are found the best available editions of texts frequently cited in histories of twelfth-century law and theology, and its secondary sources are well-chosen and up to date.