This book represents a welcome and eagerly awaited critical edition of Christian of Stavelot's important commentary on the Gospel of Matthew. Written in the mid-ninth century for the education of younger monks, Christian's treatise affords fascinating insights into the exegetical methods and didactic ideals of one of the most original thinkers of the Carolingian Renaissance. The new edition replaces the one printed by Migne in volume 106 of the Patrologia Latina by providing a much superior Latin text established by the editor on the basis of ten medieval manuscripts written from the ninth to the fifteenth centuries, as well as two early sixteenth-century editions, one from 1514 and another from 1530. The complete text of the work is preserved in seven of the manuscripts and in the editio princeps from 1514. All medieval witnesses seem to originate from Benedictine monasteries, which suggests a well-defined pattern of circulation.
The critical edition of Christian's commentary on Matthew is preceded by an Introduction which contains the following useful components: a discussion on the identity and the name of the author (pp. 7-11), a brief but clear presentation of the manuscripts used for the edition (pp. 15-21), an outline of the relationship between the manuscripts accompanied by a stemma codicum (pp. 23-31), and finally a short exposé on the Vulgate text used by Christian, his sources and knowledge of Greek, as well as the orthography adopted in the edition (pp. 31-42). The Introduction is however missing a section on the rationale employed in constructing the various critical apparatus that accompany the text, on which more below. From the section on the relationship between the manuscripts it becomes apparent that one witness (Wolfenbüttel, Herzog August Bibliothek, Weissenburg 42 = W) represents an independent branch in the textual tradition of the work. Being copied in the ninth century, this also is the earliest codex, which the editor uses as his base manuscript both for establishing the text and for solving issues of orthography. From the other two branches, branch A comprises manuscripts from the tenth, eleventh, and twelfth centuries, which all provide useful readings for the edition, whereas branch B represents a later development in the textual transmission of the treatise, being almost entirely composed by manuscripts copied in the fourteenth and the fifteenth centuries.  Two witnesses used by the editor are not included in the stemma codicum, i.e. the editio princeps of 1514 (= E) and the fragmentary manuscript Biberach 5, saec. XIVin (= B). In the case of E, the omission is explained by the fact that it is impossible to determine where precisely the manuscript used by the first editor, Jacob Wimpfeling, fits into the stemma, even though its text seems to be related to the one preserved in branch B (Introduction, p. 25). As for manuscript B, since its relationship with branch A in general and codex M in particular is inferred by Huygens on p. 20 of the Introduction, its exclusion from the stemma seems somewhat unjustified and unhelpful.
The edition is followed by an appendix called Rariora et Notabilia, which presents many interesting instances of medieval Latin usage (pp. 539-553). This is a most useful addition to the volume. After the Appendix the editor includes four separate indices (pp. 555-609): first, a list of the principal passages discussed in the Introduction and the Appendix; second, a list of biblical quotations and allusions; third, a list of non-biblical references; and finally, a detailed General Index which presents a variety of religious topics, biblical places, biblical personages and other historical figures, Classical and medieval authors and works, as well as modern scholars. A particular problem appears in the list of non-biblical references which does not include the sources which Christian uses passim in his treatise. These most often cited works are instead mentioned in the Introduction (pp. 47-48), but if the reader wishes to know how many times Christian borrows from, for example, Rabanus Maurus's Expositio in Matthaeum, she has to find and count the instances herself. The same holds true also for, among others, Jerome's Commentarii in Mattheum and Bede's In Lucae/Marci euangelium. This unfortunate situation could have been avoided quite easily by adding only a few more pages to the source index. The other indices are also marred by some omissions but these are minor imperfections in comparison.
As already mentioned, the Latin text of this new critical edition of Christian's commentary on Matthew is an excellent advance in comparison to any version printed before. The editorial decisions are sound and the outcome is most satisfactory from the linguistic point of view. The orthography is not completely consistent but this is inevitable in cases where the editor follows the spelling of a base manuscript. The entire edition is well organized and easy to use. The Latin text is accompanied by one source apparatus and two critical apparatus. The first apparatus criticus exhibits the variants which the editor considers useful for establishing the text, while the second apparatus criticus presents readings which are of interest for various textual reasons but which are inconsequential for the edition. Thus, the second critical apparatus contains readings found mostly but not exclusively in the early printed editions of the text (E and E2) and in manuscript P (Paris, Bibliothèque Sainte-Geneviève 71, saec. XII), which is a witness displaying a number of unusual characteristics. 
A careful examination of the different apparatus included in the edition reveals some problems. First, the references to the Bible and the other sources used by Christian are combined in one common apparatus fontium which is a reasonable decision for this particular text as it seems to draw upon relatively few previous authorities. It is however unusual and somewhat startling to find here also references to modern scholarly studies, such as articles by J.-P. Bouhot (p. 157), F. G. Cremer (p. 200), and D. C. Van Meter (p. 446), to mention only a few. This type of information has no place in the apparatus fontium. The editor should have incorporated it either in the Introduction or in a Bibliography, which his edition is unfortunately lacking. Other comments which should be removed from the source apparatus are the editor's translations, grammatical clarifications, and other explanatory notes.  All of these remarks could have been gathered in an appendix of annotations at the end of the edition; some could have been added to the editor's own Rariora et Notabilia. In short, it becomes apparent that the apparatus fontium is not really a source apparatus but a place where practically any type of miscellaneous information was included. At the very least this situation should have been explained in the Introduction.
The same holds true also for the apparatus criticus. The majority of the variants are presented without lemmata, a practice which prevents the reader from understanding at a glance the textual decisions made by the editor. Having to go back to the text in order to identify the word or the expression to which the critical apparatus refers does not encourage the use of this particular section of the edition. The lemmata seem to be reserved for additions, certain types of transpositions, and some more complex and potentially confusing cases. It is generally a better policy to provide lemmata for all variants included in the apparatus criticus, but when the editor decides against such a global approach, he needs to explain his rationale to the reader.
It is unfortunate that so many inconsistencies and careless mistakes, found mostly in its support sections, such as the various apparatus and the indices, should detract from this important critical edition which otherwise presents a highly reliable Latin text. Scholars interested in Christian of Stavelot's exegetical insights and educational ambitions will be well served by it, readers with an interest in the editing of texts perhaps not so much.
1. The exception here is manuscript H, the so-called Codex Hesketh, written in the second half of the eleventh century. For more information on this interesting codex, see Introduction, pp. 17-18 and 29-30.
2. The text preserved in this manuscript and its importance for the edition is discussed in the Introduction, p. 29.
3. For example, p. 166, 304--opus: de bonnes oeuvres; p. 153, 467-469--angariare: infinitif de but; p. 109, 465 ille: Herodes Antipas or p. 201, 228 Jean-Baptiste. The examples can be multiplied.