This monumental, lavishly produced volume tackles a ubiquitous but little-sung aspect of medieval culture: the diagram or “imagetext,” to use W. J. T. Mitchell’s term. Difficult to define, such artifacts may include anything from a rough table scribbled in a student’s notes to an elaborate glossed Bible page, from a world map to the geometric frame of a stained glass window. The anthology, which began in 2014-15 as a project of the Israel Institute of Advanced Studies, brings together 19 art historians, scholars of Judaica, and historians of science to explore how medieval and early modern knowledge was visualized in a wide variety of contexts.

The essays are divided into four sections. The first, “Visualization between Mind and Hand,” includes an essay by Mary Carruthers, “Geometries for Thinking Creatively,” that relates diagrammatic forms to memory and cognition, along with a case study by Lina Bolzoni on the memory theatre of the Renaissance humanist Giulio Camillo. The third essay, “Mindmapping” by Jeffrey Hamburger, is a rich theoretical piece to which I will return.

Section 2, “The Iconicity of Text,” will interest historians of the book. It includes six chapters: by Beatrice Kitzinger on two Gospel codices produced c. 1000; Lesley Smith on glossed Bible manuscripts of the twelfth century; David Stern on the glossed Talmudic page; Ayelet Even-Ezra on the “horizontal tree diagrams” employed by scholars and students across many fields; Yuval Harari on paratexts in Jewish magical manuscripts; and A. Mark Smith on the difference made by the print revolution. In section 3, “Graphic Vehicles of Scientia,” the focus shifts to the history of science and the quadrivium. Its five chapters are by Barbara Obrist on cosmological diagrams, Marcia Kupfer on world maps, Faith Wallis on calendar science and the computus, John Haines on musical neumes and the Guidonian hand, and Peter Murray Jones on medical diagrams.

Section 4, “Diagrammatic Traditions,” is a miscellany. Linda Safran offers a prolegomenon to Byzantine diagrams, a virtually untouched field. Madeline Caviness looks at “templates for knowledge”--abstract forms such as architectural plans, the ruling of manuscript pages, and her particular subject, the armatures of stained glass windows. Adam Cohen and Lucy Freeman Sandler examine the types of diagrams perhaps most familiar to medievalists, those in Romanesque and Gothic religious manuscripts. Finally, J. H. Chajes studies the evolution of the ilan,or kabbalistic tree, as a unique Jewish genre of the late medieval and early modern periods.

Given the heft of this volume, weighing in at over 500 pages, summary is impossible. Many of its essays are highly specialized, so I may be one of the few who will ever peruse it cover to cover. Scholars in some areas will want to read across its formal divisions. For example, Bolzoni, Caviness, and Sandler all address the role of numerology, while Stern, Harari, and Chajes discuss Jewish manuscripts. Jones, Stern, and A. Mark Smith all straddle the line between manuscript and print culture. But a panoptic reading can bring recurrent themes into relief and call attention to surprising analogies across disparate fields.

The chapters of Jeffrey Hamburger and Adam Cohen do the most important theoretical work. Hamburger’s essay on “Mindmapping” begins with two diagrams in a letter that his mother wrote as a child, separated from her parents to escape the Nazis. He compares one of them to a T-O map from a manuscript of Isidore of Seville, which has the same visual structure, and the second to a diagrammatic drawing by Paul Klee. The takeaway is not just the universality of diagrams but their potential to embody a whole Weltanschauung in simple form, expressing affective states as well as logical relationships. Medieval diagrams, Hamburger argues, “should be viewed not only as tools for thinking and certainly not solely as representations of knowledge but also as vehicles of deeply held desires.” They “deal with process, both in the world and, no less importantly, in the mind” (64). That is why one of their key features is directionality. Few diagrams can be grasped at a glance, for the eye and the mind are meant to follow particular paths. This insight is fleshed out in numerous other places, such as Caviness’s discussion of the “feathering” process (like a dog tracking a scent) that the eye must follow to perceive the complex design of a window (409), or Chajes’ account of the kabbalistic operator’s “ritualized participation in the unfolding of the Godly realm” as he works the pathways linking the ten sefirot (450).

Adam Cohen’s chapter on “Diagramming the Diagrammatic” observes, following Fritz Saxl and C. M. Kaufmann, that even though diagrams existed long before the twelfth century, they are a highly characteristic feature of Romanesque art. To show how difficult it can be to distinguish between the pictorial and the diagrammatic, he compares several depictions of Noah’s ark inspired by Hugh of Saint-Victor. Cohen’s proposed “diagram of the diagrammatic” is a spectrum that proceeds from pure text to pure image by way of the simple diagram, the imagistic diagram, and the diagrammatic image (388). All four types (beyond the pure text) are illustrated by the first three folios of the same manuscript, Honorius Augustodunensis’ Clavis physicae (Paris, BnF MS lat. 6734, fols. 1v-3v). Every diagram involves a balance between text and image, but that balance shifts progressively toward the latter as the page becomes more densely pictorial. Complicating his schema, Cohen then introduces further refinements, the “diagram plus” and the “image minus.” Such famous twelfth-century books as Lambert of Saint-Omer’s Liber floridus, Conrad of Hirsau’s Speculum virginum, and Herrad of Hohenbourg’s Hortus deliciarum “exploit the full spectrum of all these devices,” not to mention the writings of the Victorines, William of Conches, Hildegard of Bingen, and Joachim of Fiore (394). Curiously, Bernard Silvestris and Alan of Lille do not use them, but those authors worked outside of monasteries where the diagrammatic habit of mind flourished most intensely. Cohen here points intriguingly to the double sense of figura,meaning both a diagram and a typological relationship of the kind central to twelfth-century monastic exegesis.

Lucy Freeman Sandler’s chapter on Gothic diagrams, “Religious Instruction and Devotional Study,” takes up where Cohen leaves off. She shows that his distinction between the “imagistic diagram” and the “diagrammatic image” is also, at least in part, a distinction of class. In workmanlike manuals for priests, diagrams tend to be sketchy, uncolored, and sparing with pictorial elements. On the other hand, “highly finished pictorial imagery is found in deluxe manuscripts, made for lay owners, or for wealthy clerics” (429). The same diagram might appear in different books in more diagrammatic or more imagistic forms, depending on their quality and price. One example Sandler chooses is the Tree of Life: Christ crucified on a living Cross whose green, flowering branches are labelled with biblical verses and adorned with fruits of the Passion. Inspired by (though not originally included in) Bonaventure’s Lignum vitae, the Tree of Life image “added instructional and affective value to the words of the text, and facilitated recollection” (432). A survey of manuscripts shows a fascinating progression from Bonaventure’s unillustrated text, to the same text with an added diagrammatic illustration, to the free-standing diagram without the text, and finally to a new, simplified text written expressly to explain the diagram.

While it is hardly surprising that the body of Christ figures in devotional diagrams, other bodies also receive diagrammatic treatment. Peter Murray Jones’ survey of late medieval and early modern medical books introduces the Zodiac Man, the Wound Man, and the Disease Man, figures designed to show which parts of the body were influenced by each constellation and how to treat their wounds and disorders. Medical texts, like devotional books, span the gamut between sparsely or non-illustrated texts for ordinary practitioners and lavishly illuminated books for courtly patrons. The medical calendar, a fifteenth-century vernacular genre with woodcuts, overlaps with the Book of Hours, including such diagrammatic features as computational data for the twelve months, complete with golden numbers, dominical letters, lunar letters indicating phases of the moon, and saints’ days, followed by a zodiac table and a regimen offering medical and astrological information for every month. The cheapest images were single-sheet broadsides, used for almanacs and prognostications, that reached a wide audience although, because of their ephemeral nature, few survive.

Paired essays by Lesley Smith and David Stern compare the mise-en-page of analogous books: the twelfth-century glossed Bible and the early modern glossed Talmud. A fully glossed Romanesque Bible, meant for high-level academic study, might include the Vulgate text, Jerome’s “Hebraican” translation, Peter Lombard’s Magna glosatura (an expanded version of the Glossa ordinaria), the Lombard’s “footnotes” in a parallel column, and cross-references to other parts of the Bible, all differentiated by a hierarchy of script sizes, colored inks, ornamented initials, and page layouts indicating their relative importance. Every page was a unique construction, and Smith demonstrates that by around 1160, Parisian scribes had mastered the art of arranging pages to accommodate the text and its glosses without waste of space or loss of legibility, “an extraordinary feat of graphic imagination and skill” (123). By the thirteenth century, however, a return to simplicity set in as the Dominicans reverted to a simple, double-column lemmatized commentary format--easier to produce and more suitable for preaching, rather than monastic exegetical study.

About a century after Christians abandoned the intricate glossed format, Jewish scribes adopted it for the Talmud, designing each page to include the Mishnah and Gemara, surrounded by the commentary of Rashi on the right side and the Tosafot on the left. Apparently, Jews became aware of this page layout when moneylenders accepted expensive Latin manuscripts as collateral for loans. Even if they couldn’t read Latin, the Jews could observe the complex design and ask their clients about it. Like the Christian manuscripts, their Jewish counterparts demanded immense scribal ingenuity. A mise-en-page initially adopted for Bibles thus came to be used for the Talmud in what Stern calls “a kind of deconstructed, almost cubist rendering of the Glossa format” (144). He goes on to show how this new layout, which survived the transition to print, made the Talmud into an Ashkenazi document because even the Sephardim now studied the Ashkenazi Tosafists (disciples of Rashi). Further, the Talmudic page with its conflicting commentators “turned the Glossa format into a site of dialogical combat” (152). Unlike Christian glossators, who aimed to produce an authoritative exegesis, no single Jewish commentary obtained the same stature as the Magna glosatura, and there has never been a consensus interpretation. Instead, the complex mise-en-page of the glossed Talmud encouraged the development of pilpul, the dialectical practice of working through the rabbis’ contradictions to arrive at an apparent (though never lasting or definitive) resolution.

Underlying this practice are two theological postulates, which Stern calls the “omni-significance” and “perfectness” of the Talmud. When discrepancies emerge, they can be only apparent, not real, challenging the mind to reconcile them. Similar postulates reappear in cosmology. Like Scripture, creation should reveal the traces of a perfect Creator, which meant--in a Platonic and Ptolemaic world-view--that the planetary orbits had to trace perfect circles. Since they did not, Barbara Obrist writes, “observed erratic planetary motions as well as change in speed and direction were assumed to be mere appearances, that is, optical illusions” (232). The task of astronomers was to “save the appearances” by devising hypotheses to explain the observed phenomena, such as epicycles and eccentrics. This accounts for the bewildering complexity of some astronomical diagrams. Even Adelard of Bath, who had a good knowledge of Arabic and wrote a technical treatise on the astrolabe, tried mathematically to justify the regularity of planetary movements, despite their observed oddities. But some readers might be as surprised as I was to learn that, as early as Martianus Capella, some astronomers realized that Venus and Mercury orbit the sun and not the earth (236).

Formal analogies between media and disciplines emerge both within and across the chapters. Madeline Caviness shows that the design template of a rose window, featuring circles and quatrefoils, could echo the exegetical wheel diagrams in manuscripts and might in turn be replicated in the design of liturgical objects, such as paten and monstrance, handled by the celebrant below. John Haines compares the famous Guidonian hand, which uses the 19 joints of the fingers to signify musical pitches, to a “computus hand” that adapts the same joints to the 19-year cycle required to harmonize lunar and solar calendars (332). J. H. Chajes likens the elaborate kabbalistic trees of the sixteenth century, produced on long parchment rotuli, to finely wrought world maps painted on the same medium. Interested readers can turn to Marcia Kupfer for more on the mappa mundi or Faith Wallis on the computus. All these disciplines had an esoteric dimension, whether linked to the intricacies of biblical exegesis, cosmological speculation, or magical practice. Although we may think of diagrams functioning to simplify and clarify systems of knowledge, they could also do the reverse. Haines notes the remarkable fact that the Guidonian hand was always a left hand. Some commentators associated this with secret, unfathomable knowledge reserved for the few.

Nevertheless, in many fields the development of diagrams reached a pitch of complexity at some point, often in the twelfth century, before a reaction set in. As we have seen, Lesley Smith observes a thirteenth-century return from elaborately glossed biblical pages to a much simpler format, which she connects with a shift from contemplative exegesis to pastoral preaching. Similarly, Caviness finds that in thirteenth-century cathedrals, the highly complex programs of twelfth-century glass are no more. The windows of Chartres and Canterbury “call for slow, deliberative, and even contemplative patterns of reading,” while in lay cathedrals the iconography is simplified--and coarsened, as the place of the Jews deteriorates (424). A. Mark Smith sees a similar shift in the transition to print culture. Using Alhacen’s treatise on optics as an example, he compares a dense, heavily abbreviated manuscript with an early print version that makes both text and diagrams easier to follow--but also to skim. Print culture, he concludes, created an information overload similar to what we experience today, in kind if not in degree. As many more books became available, readers “could no longer afford to devote the time necessary for the intense, contemplative reading required by manuscripts,” but lost patience in a quest to grasp the heart of the matter quickly (227).

As for the present volume, it amply rewards slow, contemplative reading (it took me an entire month)--but it will also be a welcome resource for specialists seeking quick guidance in any one of its numerous fields.