Xavier Batllo presents here, with some small modifications, his 2012 Angers Catholic University doctoral dissertation. This useful study has an evocative first paragraph based on Gregory's self-description in a letter. It imagines Gregory, now a sick man with kidney trouble, and saddened by the recent death of his brother Basil, contemplating the landscape from his window; seized by a phrase in the volume open beside him he begins to dictate his response to it. We are to suppose that the volume in question is Eunomius' recent answer to Basil's twenty-year-old rebuttal of his Apology and that the phrase occurs in the long passage that Gregory quotes in his Contra Eunomium I (paras 151–4 in the Jaeger edition), subjects to sustained polemical analysis and thence moves on to explain and affirm his own position. Expressing himself in elevated and chiselled language Eunomius summarises the theology that he had maintained in somewhat less technical style in the original Apology: three substances, arranged in order of ontological value with appropriate accompanying causal powers. Batllo's title neatly picks out the scheme: three on a ladder of being with the lowest subordinate to the second and the second to the first. The passage does not designate these three as Father, Son and Holy Ghost but leaves that to be inferred. Gregory responds to this with objections the weakness of which Batllo gently points out. As he also shows, Gregory, too anxious no doubt to win an argument that he habitually describes in terms of a wrestling match, is prone to wilful misunderstanding of his opponent and disingenuous modification of his words. That could, doubtless, have been seen at the time but the conditions of the contest did not allow for a re-play. Gregory's positive answer was shaped in terms of the grand disjunction of ‘created’ and ‘uncreated’ and the graduated distinctions within the created of spiritual and corporeal. This positive response is considered at length in the last and perhaps most interesting chapter of a book in sympathy, but of a candid sort, with its subject. Batllo says little that is fresh where there is little fresh to say, Eunomius having been amply served in recent years and Gregory in controversy with him likewise. He summarises reliably the information about church historical background relevant to his theme and looks judiciously at the dogmatic antecedents of Eunomius, finding him to be a Christian theologian and not the logic-chopper of ancient caricature and certainly not one grossly out of touch with the Christian consensus of his time. Newman could find a good word for Eunomius' loyalty to his convictions if not for his arguments. This good monograph is by its nature, as a limited study in depth of a few lines, probably not the best place to embark on the Eunomian controversy, though it has plenty to offer those who choose it. I find the most arresting intuition of Eunomius to be his sense of the absoluteness of ultimate Godhead, which he expressed finely in the Apology. Batllo says in conclusion that though Contra Eunomium I is not among the most highly regarded works of Gregory it none the less certainly has some of his best pages. Yes, but also certainly some of his worst. Gregory's best and most instructive arguments are to be found, in my opinion, in his third book Contra Eunomium; but that opinion has no bearing on the quality of this book.