Since 2008, Stockholm University has been the home of the Ars Edendi ("Art of Editing") Research Programme, which investigates the challenges of editing medieval Greek and Latin texts.  The editorial methodologies established by Karl Lachmann (1793-1851) and Joseph Bédier (1864-1938) were designed primarily to communicate in print the works of classical and medieval authors whose style of prose or verse was stable and consistent. Their principles of text editing did not take into consideration the wealth of para-textual material present in medieval manuscripts, including glosses, scholia, and notes. Nor did their methodologies account for the fact that many medieval works were not original compositions, but patchworks of quotations and sayings that varied considerably from manuscript to manuscript. Faced with these complexities, scholars at Stockholm University and like-minded text editors in Europe and North America are wrestling with the challenges of rendering in print medieval Greek and Latin texts that defy the conventions of traditional methods of text editing.
The volume under review presents a dossier of their solutions, a "casebook" of nineteen articles "designed to give readers an insight into the complications of real-life editorial practice" (xv). Each contribution offers a practical and thoughtful approach to the difficulties of editing medieval texts that challenge the conventions of Lachman and Bédier. The range of primary source materials treated in these essays is broad, encompassing works in Latin and Greek, texts both sacred and secular, with a preponderance of prose, but some verse as well. In terms of genre, the contributors grapple primarily with medieval commentaries and scholia on the Bible (Andrée), on the sequence (Kihlman), and on classical and late antique texts (Cullhed, Pontani, Hicks, O'Sullivan, and Thomsen Thörnqvist). There are also important articles on little-known collections of philosophical sayings and essays (Searby and Wahlgren), texts for liturgical use (Iversen and Jensen), patristic anthologies and other "devotional" prose works (Antonopoulou, Odelman, and Bucossi), biblical paraphrase (Dinkova-Bruun), and even charters (Gejrot).
The contributors adopt a variety of solutions to the problems posed by the texts they are editing. For example, in his article on medieval commentaries on Martianus Capella's De nuptiis Philologiae et Mercurii, which exhibit wide textual variation across the ten extant manuscripts, Andrew Hicks proposes a synoptic edition of the main branches of the tradition (139-159). As Erika Kihlman recommends in her article on sequence commentaries, in those cases where the manuscript tradition is too large and varied to construct a critical edition, the presentation of a "representative text" seems like the best solution (219-246). In her study of Peter Riga's Aurora (a versified commentary on the Bible), Greti Dinkova-Bruun confronts an author who added to his text over the course of his lifetime, resulting in no fewer than three "main versions" of the poem, as well as new redactions produced by the additions of later continuators (97-120). She suggests printing different versions of the poem in succession so that readers can experience theAurora as Peter left it, while also comparing how later poets introduced new material to the text. What is most striking about the volume is how few of its contributors (two of nineteen) suggest recourse to digital technology to solve their editing problems. Barbara Crostini envisions her edition of Vaticanus graecus 752, an eleventh-century illuminated Greek catena to the psalter, as a digital project because the print format is ill-suited to presenting the dynamic between text and image in the manuscript (55-71). Likewise, Denis Searby proposes a digital edition of an anonymous collection of Greek philosophical sayings as a way to organize the individual components of an unstable corpus of texts with little evidence of how they relate to one another. Other than these two examples, the contributors to the volume seem firmly wedded to traditional print media for the presentation of medieval text additions. 
As a "case book" of innovative editorial practices, this volume is not intended to be read from cover to cover. In light of this, the editors have done a magnificent job of indexing the individual articles to facilitate their use by scholars who dip into the collection to find solutions to their own editing issues. Each contribution begins with a series of helpful summaries under the following categories: type of text and textual material considered in the article; the date of the sources, both their origin and the manuscripts that provide evidence of their later use; specific witnesses used in the case study; the methodological problem considered in the contribution; the solution imposed by the author; and cross-referencing to other articles in the book dealing with similar problems. In addition, there is a useful glossary of technical editorial terms at the end of the book alongside a general index and an index of the manuscripts cited by the authors. Lastly, high-quality color images of manuscript pages adorn many of the articles in the book. This handsome volume is a testament to the industry of the Ars Edendi Research Programme, which has done so much over the past decade to draw attention to the importance of editing medieval Greek and Latin texts. Scholars engaged in text editing and manuscript studies will find many puzzles in these pages. While readers may question some of the solutions posed by the contributors, they will nonetheless benefit significantly from the thoughtful consideration of the problems of presentation and readability faced by anyone attempting to mediate a medieval text between the manuscript and the printed page.
1. For further background on this program, see my review of the first two volumes of the Ars Edendi Lecture Series in TMR 14.03.30: https://scholarworks.iu.edu/journals/index.php/tmr/article/view/18560
2. For an example of digital approaches to text editing, see Elena Pierazzo, Digital Scholarly Editing: Theories, Models, and Methods (Farnham: Ashgate, 2015).