Vacarius was born in the early twelfth century in northern Italy and probably educated in Bologna or another northern Italian school. In the 1140s he immigrated to Canterbury to work in the curia of Theobald, archbishop of Canterbury. English chroniclers report that Theobald brought Vacarius to England because of his dispute with Henry, bishop of Winchester, over Henry's status as a papal legate. Taliadoros thoroughly examines Vacarius' activities in England and discusses the rich English historical literature that this Italian jurist has inspired. The core of his book, chapters ii, iii and iv, justify ‘law’ and ‘theology’ in his title. Chapter ii is primarily based upon his analysis of Vacarius' Summa de matrimonio, principally a canonical treatise. There are only a half dozen references to Roman law in his Summa; almost all the allegationes are to the marriage causae in Gratian. Taliadoros's analysis of Vacarius' marriage treatise is subtle and revealing. He argues that Vacarius was critical of the canonists' terminology and of their general theory of marriage. Vacarius' critique is based primarily on Roman law and logic. Taliadoros notes that while Vacarius was in the employ of the archbishop of York, Alexander iii sent several decretals to York that decided marriage cases. In these cases the pope began to develop a jurisprudence of marriage that focused upon consent. Taliadoros compares Alexander's conception of marriage with the doctrine that Vacarius created in his marriage tract and concludes that Alexander and the jurist used different approaches to reach the same conclusions. The chapter on marriage reveals very little about Vacarius the theologian; but it does reveal that he was very familiar with Gratian. Chapter iii, on Christology, and chapter iv, on Vacarius' polemical tract in which he takes to task the views of his old friend, Ugo Speroni, are primarily theological as argued by a jurist. As I read chapter ii with Maitland's edition of Vacarius' Liber pauperum at my elbow, I was struck by a major problem that in no way reflects upon the value of Taliadoros's work. Maitland's edition needs to be redone. It is completely inadequate for doing the kind of work that Taliadoros wished to do in chapter ii. Justinian's Codex treats marriage in book five, titles 1–15. Maitland edited the glosses that he found in the manuscripts of the Liber pauperum but he did not edit the texts taken from the Codex or Digest from these titles, and, most important, he did not edit the authenticae Vacarius used that were added to the margins of Codex manuscripts during the twelfth century. The authenticae are important because they represent the work of Irnerius (perhaps) and the early jurists (certainly) to update and to interpret the texts contained in the Codex. Vacarius underlined their importance for jurisprudence when he included the roughly 170 authenticae in his Liber out of over 200 in the Codex (twenty-three of the twenty-seven were added to the Liber pauperum's marriage titles). In contrast Vacarius included only a small percentage of texts from the Codex (and even fewer from the Digest) in his book. Maitland noted that Vacarius did not include in his work the exact texts that he found in his source. For any analysis of Vacarius' thought, these changes might be of some importance. The only way, however, to squeeze any information out of Maitland's edition is to make your own primitive edition of the text based on the incomplete information that Maitland provides. With a new edition of the Liber pauperum Taliadoros could write a follow-up volume on Vacarius the Jurist. That project, however, would be impossible with Maitland's edition.