David Ganz: Medien der Offenbarung. Visionsdarstellungen im Mittelalter, Berlin: Dietrich Reimer Verlag 2008, 436 S., 64 Farbtafeln, 176 s/w-Abb., ISBN 978-3-496-01376-1, EUR 69,00
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This is a sweeping study of a literally spectacular subject: the representation of visions in the art of the Middle Ages. At the same time, it is important to be clear about what it is not. Ganz' study does not, nor, apparently, was it intended to provide a history of theories or theologies of vision and visionary experience, let alone of visions in the Middle Ages, although it does, by necessity, touch on these subjects and contributes to them in novel and interesting ways. Nor does it dwell at any length on the history of literary representations of visionary experience, a more curious omission, given that the overwhelming bulk of the material discussed comes from illuminated manuscripts, some of which contain such texts. It would, however, be difficult to demand more of a book that is already so ambitious in scope.  What Ganz offers is something that has never been previously provided, at least not on this scale: a history, not of visions per se, but rather of the means and modes (the author's preferred term, on which more below, is "Dispositiv") by which they were represented and communicated to medieval viewers.
As Ganz notes, in the Middle Ages vision was a flexible concept that ranged in its associations and frame of reference from the empirical sense of sight (corporeal vision, to use the familiar threefold Augustinian hierarchy) to imaginative vision, which included dreams, memory and what medieval commentators called spiritual vision, to intellective vision: the immediate form of vision enjoyed by the angels, the souls of the just in heaven (visio beatifica) and, it was believed, a privileged few in this life. Ganz focuses, as art historians must, not on the highest form of vision, which by nature remains unmediated and, hence, in large measure incommunicable, but rather on those forms of visionary experience that are mediated, that is, conveyed by some sort of intermediary. There is, however, a double mediation involved: first, that of the vision itself to the visionary (whether a biblical prophet or a mystic), and second, that of their experience to their followers, readers, emulators and interpreters. The necessity of some form of mediation, dependent on images, is precisely what led some medieval commentaries to deny vision, in whatever form, the highest rank on the scale of ways and means of knowing God. In light of their mediated or constructed character, representations of visions can thus have two closely related, but not necessarily integrated, goals: on the one hand, to share with a given audience something of what the visionary purportedly saw or experienced (a process that in itself requires mediation and recreation), and on the other hand to permit members of that audience in some way to share or participate in that experience. Bearing in mind that mysticism and visionary piety are distinct phenomena (albeit to what degree is a matter of debate), the distinction drawn here is analogous to that between mystagogy, i.e., teaching about mysticism (which, we do well to remember, is a modern, not a medieval, term) and mysticism itself, founded in experience (cognitio dei experimentalis, to use a term coined by Bonaventura). Another way of drawing the same distinction might be to differentiate between the object and subject of visionary experience: a visionary can have a vision of, say, the Trinity, which could be said to be the object of his or her vision and which to a believer has an objective "reality", but the subject of the same vision extends to include his or her experience, which is another matter, and has a subjective dimension.
To what extent any given image attempts to (or succeeds in) representing one, the other or both dimensions of the visionary is not simply a question of artistic competence or conventions, but also of historical context, in short, the expectations that viewers brought to both the making and viewing of such images and, more generally, their attitudes towards the capacity of the visual arts in general to represent or at least hint at the realm of the invisible. These attitudes hardly remained consistent throughout the Middle Ages and changed, not simply in response to transformations in doctrine, exegesis, theological teaching or pastoral prerogatives, but also, as Ganz has occasion to observe, to transformations in practices of representation.
In short, images never simply reflect or illustrate the texts that transcribe visions, let alone the visions themselves, they also have the capacity to provoke, shape and structure them. In addition to reporting on visions, they can invite viewers to share in them by way of initiation and participation. The history of representations of visions is thus a multifaceted one. In addition to providing a history of a particular form of religious practice that has its origins, at least in the Judeo-Christian tradition, in the great visions recorded in the prophetic books of Jewish Scripture, it can also provide a history of vision and of attitudes towards vision (what in modern parlance has come to be called "visuality", by way of emphasizing its constructed, conventional character) and, not least, towards images themselves. It is one of the central paradoxes, yet also possibilities, of Christian art that it is focused simultaneously and with such intensity on both the visible and the invisible. An image that insists too much on the former at the expense of the latter runs the risk of being reduced to an idol. This was, in effect, the position taken by iconoclasts, who argued that a material image could not circumscribe the immaterial. As is well known, iconodules countered with the Incarnation, arguing that to refuse to accept images of Christ as man was tantamount to denying the doctrine of the word made flesh. Artists, however (or if one insists on avoiding that term, the craftsmen who produced images), had to find ways to suggest the immaterial through the material, not by invoking various theological metaphors summoned in defence of images (which on occasion they did), but through the means and methods of their art. It is these means or methods (or some of them, at least) and the ways in which they changed over the course of the Middle Ages that are in large measure the subject of Ganz' book.
Ganz' study is presented as a grand triptych that unfolds over four hundred closely argued pages, amply illustrated, including sixty-four excellent color plates. The first part, "Schrift-Bilder", in many respects the most original, focuses on representations of prophet visions rooted in Scripture from the early Middle Ages, beginning with minor exceptions in the Carolingian and Ottonian periods.  Focusing almost without exception on representations of visions in manuscript illumination from the Ottonian period through the twelfth century, these chapters (1-4) consider both the illustration of visionary texts and the ways by which those illustrations root the sources and experience of vision in the reading of Scripture in ways that are in keeping with monastic habits of meditation and contemplation (itself by definition a form of "vision"). Among the materials discussed are the extraordinary illustrated Ottonian commentaries on Isaiah, Daniel and the Song of Songs now in Bamberg, of which Ganz provides a compelling account, linking prophetic imagery and political ideology. Also discussed in this section are early medieval Apocalypse manuscripts, again, that in Bamberg, as well as that in Trier, the Beatus commentaries, the illustrated manuscripts of Hildegard of Bingen's Scivias, and prophetic/typological imagery in twelfth-century bibles.  Ganz sees the manuscripts from Bamberg as a set of sorts whose illustrations map a progress from prophecy to direct vision of the Godhead. The argument could have been made still more convincing had Ganz made use of Bernard Bischoff's often overlooked article on the Evangelist portraits in the Gospels of Otto III, an important source for some of the imagery employed in the Bamberg commentaries that Bischoff saw as stemming in part by a passage in Paul (Hebrews 12:1), in which the apostle speaks of being surrounded by a "cloud of witnesses."  Seen in this light, the imagery elaborated in the commentary manuscripts derives, indirectly, from a form of word illustration. It also embodies the dynamic of concealment and revelation that is inherent in the prophetic discourse of the commentaries themselves. Clouds are but one of the many devices deployed to such ends in medieval art; curtains are another. Ganz discusses the metaphorics of veiling and unveiling, but should have included some discussion of the numerous images that incorporate ingenious variations on the cortina motif, a very prominent feature in medieval art inherited from Antiquity, especially in the early Middle Ages, and frequently employed to denote a liminal passage from one "level" of experience or reality to another. 
The second section, "Seelen-Räume" (chapters 5-9), traces a process of increasing emphasis on subjective experience, focusing on imagery of interiority. Such imagery is well-known from the later Middle Ages, the primary example being the hortus conclusus, but Ganz shows how other metaphors, notably those that draw on architectural imagery, have roots in the early Middle Ages. Among the formal and iconographic devices discussed by Ganz in this section are frames, mandorlas, the motif of the dreamer asleep on his or her bed (most notably, Jesse), the diptych, evocations of mirrors, and serial imagery (e.g., in Apocalypse illustrations).  Interiority is not something that can be taken at face value as a constant in human experience, and it has come under withering critique from some quarters, including feminist criticism.  The same holds true of subjectivity.  Ganz does not delve into these issues, but his careful analysis of the devices through which interiority was constructed and created would be useful to such critiques in so far as it underscores the conventional, inherited character of much of the imagery involved as well as the sophistication with which it was manipulated, by artists as well as pastoral authors. Visions had public as well as private purposes.
Especially original is Ganz' discussion of the manuscript opening as a device that was used to dramatize and enact visionary subject matter. Although the opening is an essential feature of the codex, it has, in contrast to the layout or mise-en-page of the single page, hardly ever been discussed as a formal or expressive device, an astonishing oversight produced in part, no doubt, by the reluctance of libraries to photograph openings on account of concern about damage to bindings.  Openings lend themselves to the contrasts that underpin and elaborate typological imagery, a relationship that Ganz touches on without, however, really giving it the emphasis it deserves. This represents a missed opportunity in so far as typological exposition, perhaps more than any other art form in the Middle Ages, fostered precisely those forms of topological disposition that are at the heart of Ganz' own exegesis. Moreover, typology is intimately linked to issues framed in terms of vision. It was in the context of typology that the "blindness" of the Jews was held up by way of opposition to the vision and insight of Christianity. The context of anti-Jewish polemic lends some of the visionary imagery discussed by Ganz a sharper polemical edge than his sometimes rather formalistic approach allows. To discuss the diptych format as a means of representing visions in early Netherlandish Painting without even passing reference to a seminal article by Craig Harbison (let alone a number of more recent contributions, for the most part by American scholars) is a glaring omission, even if one concedes that scholarship on this material has tended to overemphasis the mystical and devotional at the expense of the courtly.  The same can be said of the famous Ottonian ivory diptych in Berlin, which, if one follows William Diebold, is not typological in character, but instead represents a subtle commentary on a passage in the Gospel of John involving the persistent theme of vision. 
The third section, "Körper-Zeichen", extends the dialogue of interiority and exteriority, which echoes that of invisibility and visibility, in a series of case studies (chapters 10-13) that, by examining instances in which visions were perceived as having left visible marks on the body of the visionary, emphasize the outer at the expense of the inner. Of these, the most famous is that of the stigmatization of Francis of Assisi. This is followed in the trajectory of Ganz' argument by a chapter on Heinrich Seuse, whose writings were extensively illustrated and who, despite being a Dominican, included numerous motifs from the life of his Franciscan forebears (and who also borrowed part of the culminating passage in Book I of The Exemplar from Bonaventure's Itinerarium in mentis deum).  More original in its contribution because it deals with less familiar material is Ganz' analysis in the subsequent chapter of the earliest extant illustrated manuscripts of Catherine of Siena's Legenda maior, in which he discusses to what degree the images and texts insist on distinguishing Catherine's stigmatization from that of Francis. A concluding chapter focuses on the Mass of Gregory the Great. Here Ganz might usefully have cited Michael Camille's study of the transformation of Gregory's image from the early to the late Middle Ages, as it to some extent matches the contrast that he himself wishes to draw between an early medieval monastic culture of visionary experience still largely rooted in reading and that of the late Middle Ages, which is both more empirical and incarnational in emphasis. 
Ganz summarizes this section's argument as follows: "Die Tatsache, dass die Transformation des Heiligenkörpers durch Gott als heilssichernde Realie verstanden wird, belegt, dass man bereit ist, einer körperlich sichtbaren Vision einen höheren Wirklichkeitsgrad zuzugestehen als einer bloß innerlich geschauten. Neben einem neuen Ideal der Christusähnlichkeit steht dabei die Beobachtbarkeit des Körpers im Sinne von Beglaubigung und Authentizität im Vordergrund, die nun vom Bild simuliert werden soll" (281). Echoed here, if not explicitly invoked, is a much larger debate over the place of exteriority and interiority in late medieval piety at large. Right up to the Reformation, critics of late medieval piety lambasted pious practices, from pilgrimage to prayers, that placed too much emphasis on bodily exercises at the expense of what they regarded as "true interiority" (Eckhart is among the famous exponents of this creed).  "Mere interiority", to use Ganz' term, is not the issue; rather, it is, to use his own more accurate formulation, "ein elementares Vermittlungsproblem, das den Kontakt zwischen Innen und Außen, Diesseits und Jenseits, zunehmend in Frage stellt" (281).  Seuse's writings may be notorious for the way in which they describe the way in which the "diener" inscribes the Holy Name on his heart - a superficial, exteriorized sign of interiority if there ever was one - but within the structure of The Exemplar as a whole, Seuse is at pains to emphasize that this kind of outward exercise merely represents a first step along the mystical way and that in the end what matters is the ability to carry the name of Christ in one's heart. In debates reminiscent of early medieval iconoclastic controversies, critics of images argued that they stood in the way of interiority, whereas their advocates saw in them a way of conforming the interior imago to its ultimate exemplar, namely, Christ.  Images did not take sides in this debate, but they did serve as bones of bitter contention, and, as Ganz has occasion to observe, their pictorial rhetoric responded to both anxieties and aspirations regarding the place of images in Christian worship.
As should be clear from this summary, what Ganz supplies is more than just a synthesis or even a survey, but, despite some serious omissions, an overarching argument regarding general developments in the representations of vision over more than half a millenium. The outline of the argument is usefully laid out in the introduction, where Ganz poses a series of questions: "Welches sind die bildkünstlerischen Konfigurationen, die eine Vision als ein 'Bild-Medium' definieren? Inwiefern fließt in diese Konfigurationen das erweiterte Erfahrungsspektrum visionärer Bilder ein, in dem sich Geschautes oft mit Gehörtem, bisweilen auch mit Berührtem und Geschmecktem verbindet? Für eine historisch reflektierte Bild- und Medientheorie kann dieser erste Fragenkomplex nur in Verbindung mit einem zweiten sinnvoll beantwortet werden: Wann und wo werden Visionen überhaupt als Bildgegenstand ausgewählt, welche Funktionen erfüllen Visionsdarstellungen in ihren jeweiligen Kontexten?" (10) In seeking answers, Ganz gives central significance to the topological categories of place ("Ort") and boundary ("Grenze") (11). In keeping with a postulate of "Bildwissenschaft", in particular in its anthropological variant as elaborated by Hans Belting, Ganz situates the images he discusses, not only in cells, chapels and churches, but, above all, in the human imagination and memory. This is useful in so far as it allows for a complex dialogue between issues of production and reception. It is less useful in so far as, despite all the talk about media, it tends to lump together objects very different in size, function, date and context and treat them all under the very amorphous rubric of the "image".
In fact, Ganz' study is not quite as wide-ranging as his introduction suggests. He leaves largely to one side the relationship among and the hierarchy of the senses.  Even issues of function recede largely into the background. The focus is very much on the images themselves, not the persons, communities or contexts for or in which they were made (not that these are altogether neglected). As a result, Ganz foregrounds in productive ways issues of formal presentation, subjecting the images with which he deals to rigorous analysis in ways derived in part from Wolfgang Kemp , as well as Sixten Ringbom, whose pioneering discussion of devices for depicting visions and dreams Ganz generously acknowledges (17-20).  Ganz nonetheless criticizes Ringbom's formulations and, by extension, some of those developed by Victor Stoichità with reference to early modern painting, as too dependent on the modalities of illusionistic painting (18).  He rightly observes that the link between vision, visions and visionary modes of representation developed in the late Middle Ages can lead to an overemphasis on the later Middle Ages and images in which naturalism, however defined, is suspended to underscore the contrast between this-worldly and otherworldly levels of vision.
Instead, Ganz chooses to work with what he calls "topologische Konstellationen" that, in his words, "die Position des Visionärs in einem erweiterten Bezugsfeld von innen und Außen, Mensch und Gott, Diesseits und Jenseits verorten" (20). In this context, Ganz introduces a term derived from film criticism, "Dispositiv", one to which he has recourse throughout his study. Film studies have usefully been brought to bear on the study of medieval narrative (the example cited by Ganz is the Bayeux tapestry), less often on other medieval modes of representation. Quoting Jean-Louis Baudry, Ganz states (20): "Das Dispositiv wird dabei zuallererst als 'räumliche An-Ordnung' verstanden, 'in der ein Betrachter zu einer bestimmten Ordnung der Dinge so in Beziehung gesetzt wird, dass seine Wahrnehmung dieser Situation dadurch bestimmt wird. [...] Bilder konstruieren [...] eine spezifische und von Fall zu Fall unterschiedliche An-Ordnung des Betrachters." Building on this basis, Ganz distinguishes between the "Dispositiv" of those images seen by visionaries and of material images, noting that the former can only be seen once they have been "transcribed" by the latter. Here Ganz introduces two further discriminations: "Lageplan" and "Simulation". By "Lageplan", Ganz means a specific disposition (not necessarily spatial) that defines the relationship between seer and seen: "begrenzt/unbegrenzt, zugänglich/unzugänglich, Einschluss/Ausschluss, Nähe/Ferne, Zentrum/Peripherie"). By "Simulation", in turn, Ganz means a disposition or pictorial device (for the most part illusionistic, but sometimes different in kind, for example, diagrammatic), that indicates that the depicted vision involves a particular mode of vision. For most of the Middle Ages, according to Ganz, and in contrast to the early modern period, artists made much less use of "Simulation" than of relational disposition on the surface in various forms to define and structure representations of vision.
Reduced to its essential elements, namely, an acknowledgment that most of medieval art is not illusionistic and that even in its presentation of narrative, it relies largely on abstraction, diagrammatic forms, and surface arrangement, this statement is hardly novel. One is reminded, for example, of Panofsky's distinction (not quoted by Ganz), which takes as its point of departure two images, one by Rogier van der Weyden, the other from the Ottonian Gospels of Otto III, in order to highlight the difference between modern (illusionistic) and medieval modes of representation. Panofsky argued, "The unsupported figure in the van der Weyden picture counts as an apparition, while the floating city in the Ottonian miniature has no miraculous connotations."  In contrast, what interests Ganz are the formal means by which an apparition or a vision could be indicated in medieval art, not by illusionism but by other means. Whether "Dispositiv" is the most useful term he could have arrived at to describe this phenomenon is another question. In English, the closest match for what Ganz wishes to stress is the word, disposition, which means the "action of setting in order, or condition of being set in order, or the relative position of the parts or elements of a whole." Rather than a new jargon term, however, perhaps an ordinary word like "Anordnung" would have been both better and in need of less explanation. As used (or overused) in the book, "Dispositiv" is at times in danger of explaining too much. Given Ganz' definition of the term, any individual application of it might usefully have been made more precise through comparison with a broader repertory of related formal devices employed at any given time and place and not solely in images with visionary subject matter. In short, to state a truism, artistic expression remains in part a function of what we continue, for lack of a better term, to call period style.
Quibbles over terminology aside, the contrast with Panofsky makes clear that what Ganz strives for is a new way of comparing, categorizing and analyzing visionary images from widely varying contexts. As such it allows a more refined understanding of some of the formal devices that inform the visionary tradition in medieval art. This is the great strength of Ganz' book. Ganz' subtle descriptions of numerous images, whether in Beatus manuscripts or the Ottonian commentaries on Isaiah, Daniel and the Song of Songs now in Bamberg, add to our understanding of these works precisely in so far as they do not take the accompanying texts as a necessary and determining point of departure.
It is, therefore, somewhat puzzling, particularly with the benefit of hindsight, to read in his introduction his claim (22) that: "Die vielleicht entscheidende Konsequenz aus dem Dispositiv-Ansatz für eine Geschichte der mittelalterlichen Visionsbilder dürfte darin bestehen, die Betrachtung über die Grenzen des Einzelbildes hinaus auszudehnen." This extension of the field of study beyond images, Ganz suggests, includes "den intermedialen Dialog zwischen Visionsbildern und Visionstexten, wie er sich beispielsweise auf den Seiten mittelalterlicher Handschriften ergibt", and, in addition, what he argues is "die wenig beachtete Pluralität der Visionskunst, das Beziehungsnetz mehrerer Visionsdarstellungen untereinander." It could be argued, however, that both of these aspects of visionary images are among those that Ganz neglects. With regard to the second, the sequential, even serial, nature of some visionary images, especially in manuscript illumination, this is a feature to which Jérôme Baschet has dedicated several studies, none of which are cited by Ganz.  And with regard to texts, not only does Ganz exclude the large number of works that report visionary experience involving images, instead limiting himself, with few exceptions, to those, such as the texts by or about Hildegard of Bingen, Francis of Assisi, Heinrich Seuse and Catherine of Siena, that were illustrated, he also gives little consideration to the complex mechanisms by which the figures and images evoked by liturgy and exegesis, for example, of the Song of Songs, found their way into the lived experience of the monastic communities for whom these texts become second nature. No less important than the objects themselves, regardless of what words one uses to describe them, are the processes by which they came into being, which in turn involve consideration of the culture of book production and the communities of readers in which they were embedded. It could be observed that the trajectory from text to image and from reading to vision that Ganz observes over the course of the Middle Ages is one that comprehends far more material than that which he treats in his book. Ganz regularly employs the term "icontext" coined by W.J.T. Mitchell to describe complex verbal-visual objects, without, however, including Mitchell's important contributions in his bibliography.  Gothic manuscript art in general is characterized by an increasing separation of text and image, in part through the use of ruling and frames, which in turn encouraged the introduction of illusionistic effects.  The creatures that inhabit the margins have, to a certain extent, been expelled from the body of the text that they continued to inhabit in the twelfth century. In this context, his discussion of the imbrication of text and image in early medieval depictions of visions could have benefited from the literature on historiated initials. 
Another weakness of the book is that there is no substantive discussion of the many texts that testify to the visionary experience of medieval viewers in front of sculptural images. Many such images are ambiguous - does the image represent someone praying in front of an image or experiencing a vision? - but in others a host of formal devices make it clear that what is seen is seen with the inner eye. Among the most literary accounts of such experiences is Rupert of Deutz' vision of an intimate, erotic kiss at the altar immediately below an image of the triumphal cross (not a representation of a vision, but nonetheless an image that stimulates a visionary experience) and the numerous reports of visions in hagiographical texts, some of which were illustrated with representations of the reported visions (for example, the fourteenth-century Hedwig Codex).  Late medieval literature of this kind is relatively well-known, and although much of it has been mined productively by art historians, more remains to be done. For example, Gertrude of Helfta makes frequent self-conscious reference to images and to theories of visions, often employing long quotations from Richard of Saint Victor.  Less familiar are the early medieval sources, many of them hagiographic in nature, to which scholars such as Jean-Marie Sansterre continue to draw our attention.  Sansterre's publications show that many features of devotional and visionary piety that we have tended to associate primarily with the later Middle Ages in fact have deep roots in the monastic culture of the earlier Middle Ages. Also missing from Ganz' otherwise sweeping purview are those visionary texts such as the Vision of Tnugdal, not to mention a host of dream visions (such as the Roman de la Rose), that were illustrated, some quite spectacularly, as, for example, in the manuscript of the Visions of Tnugdal made for Margaret of York now in the collection of the J. Paul Getty Museum.  If there was a good reason for material of this kind to have been excluded, for example, because the visions involved are "fictional", as opposed to "real" (not that this distinction is always an easy one when dealing with medieval sources), then it should have been clearly stated. Precisely because such texts self-consciously deal with the category of fiction and its aspirations to "truth", visionary literature, its references to works of art (which are plentiful), and its illustrations would have provided a fruitful set of comparative sources.  Images within images, whether of the kind that Ganz discusses or not, are common in the visionary mode and often lend it the character of a commentary on the status of art and visual experience as such.
Ganz does not always do justice to the richness of recent debates on text-image issues in medieval art (which, it should be noted, extend to include far more than illuminated manuscripts).  One aspect of the text-image debate recognized but never quite fully addressed by Ganz involves the place of theological discourse in relation to images. On the one hand, and quite rightly, Ganz seeks to secure for images a place prior to and free from the constraints of theological debate. This is a position consistent with Hans Belting's position in Bild und Kult. A signal, if somewhat exaggerated, example is Ganz' claim that the novel way of representation the stigmatization introduced by Giotto "entstand nicht als Umsetzung theologischer Vorgaben à la Bonaventura, sondern im Kontext neuer künstlerischer Techniken, die für theologisch-naturphilosophische Diskurse der Zeit anschließbar waren" (297). This is reformulated elsewhere (307) as follows: "Die Erfindung des neuen Strahlenschemas in Assisi und seine Modifikation in der Bardi-Kapelle waren das Ergebnis künstlerischer Prozesse, die ein Nachdenken über die geometrische Projektion von dreidimensionalen Körpern auf eine zweidimensionale Darstellungsfläche voraussetzen. Erst die neuen Darstellungsverfahren der Zeit um 1300 schufen den Möglichkeitshorizont, um sich vom älteren Konzept der Bildübertragung durch die menschliche imaginatio zu lösen." To all this could be countered that Bonaventure's legend of Francis is not really a theological text. This aside, the argument is in danger of becoming circular. If the new iconography of the stigmatization depends, not on texts and the ideas that they develop, but rather on the development of new modes of representation, what in turn, one might ask, led to their emergence? This is an old debate that goes back at least as far as Thode, who argued that it was Franciscanism that prompted the emergence of early Renaissance naturalism, in short, exactly the opposite of what Ganz argues here.  Before one seeks to take sides, one could ask: why do we need to choose between the two possibilities, art or theology, in such exclusive terms?  Are we really to believe that an artist working around 1300, even an artist as inventive as Giotto, was free to reformulate an iconographic motif so central to Franciscan identity as the stigmatization of Saint Francis without any input from those who commissioned it? To insist, as some media studies do, that the medium determines all smacks of a formalism more reminiscent of the modernist credo that the "medium is the message" than of anything that can convince in the context of everything else we know about the historical circumstance in which these images were produced.
Another arena in which Ganz takes issue with a strong current in recent scholarship involves the discourse on optics. Ganz is correct to state, as he does in his conclusion, that "Ein wichtiges Argument gegen die Engführung von Visions- und Optikgeschichte ist jedoch die Tatsache, dass Optik zuallererst eine Theorie des äusseren Gegenstands-Sehens und nicht einer imaginären Schau offenbarender Bilder ist. Dass die Neuerungen der Optiktheorie ein universales 'skopisches Regime' der spätmittelalterlichen Kultur hervorgebracht hätten, erscheint damit mehr als fraglich" (391). Here, too, however, Ganz is rather too categorical. To the extent that medieval exegetes, visionaries and mystics themselves used terminology and concepts, such as intromission, derived from the discourse of optics, to characterize, even if only by analogy, visionary experiences, one is more than justified in looking to writings on optics as a relevant set of sources. The English bishop and theologian Grosseteste is only the most famous example of a convergence between theological and scientific discourse in the thirteenth century.  Moreover, it is inaccurate to suggest that optics was concerned primarily with outward appearances. Optics formed an essential part of the larger debate surrounding images, the senses and memory, in short, about the relationship between inner and outer that is central to Ganz' topological approach to visionary images regardless of their medium, whether the body of the viewer or that of the work of art. 
In fact, Ganz recognizes that theology plays a central part in the story he wishes to tell. To the degree that images and vision were central to Christianity and helped distinguish it from Judaism, at least in the eyes of medieval Christians, it was because the doctrine of the Incarnation demanded that vision and the visible be given its proper place. Albertus Magnus puts this very succinctly in his commentary on chapter one of John's Gospel, in which he paraphrases John 1.10 by linking Christ's incarnation explicitly to his visibility: "He was in the world, that is, he was made visible in the world."  Theology, it should be stressed, was not necessarily inimical to images. Some theologies, for example, that of the Victorines in the early twelfth century, played a critical role in emphasizing the indispensability of empirical experience. The Victorine validation of nature, history and experience was not simply a response to images that we, with the benefit of hindsight, characterize as "Gothic" or "naturalistic," they in part helped shape the climate in which such images became possible. With regard to visions per se, theologians were often suspicious of visionaries on account of their prophetic power, but they also understood the power and persuasiveness of images and often sought to harness them to their particular purposes.
It is easy to point to such oversights and exaggerations, and no book, not even one as long as Ganz', can be expected to include everything of possible relevance. More to the point is that a sampling of such materials would have permitted Ganz to articulate, not simply a "medientheoretisch" approach, but the medieval theory (or better, theories, as there were more than one) of vision and visions to which the images that interest him could then be seen, not as illustrating, but as responding to or at least engaging with. Here Ganz could have made productive use of Jean-Claude Schmitt's understanding of the Middle Ages as a "culture de l'imago", a useful concept precisely because it is so flexible, embracing as it does images both imaginary and material as part of a contested continuum.  In all such analysis, it is crucial to see the images not simply as supplements to literary culture, but as active participants in dialogue and debate. The texts in turn must be read as responding to a pre-existant culture of images. Ganz is aware of all these issues and considerations, and in places, for example, his discussion of the ways in which the illustrated lives of Catherine of Siena do not correspond to the details or strictures in the texts, incorporates them into his analysis. They are never, however, clearly articulated as considerations or principles of method governing the entire project.
Perhaps more difficult to understand, and more important, because it goes to issues of method, are other omissions, not of texts, but of images. In a book that repeatedly insists on what it calls a "medientheoretisch" approach, it is puzzling that so many of the examples discussed, often with great subtlety and visual sensitivity, come from a single, albeit, significant medium: that of manuscript illumination. Given the book's ostensible emphasis on the ways in which the choice and conditions of various media inflect representation, the lack of comparisons among media seems a glaring oversight. Only a handful of examples come from the realms of sculpture or wall painting, both of which could have offered a great deal more relevant material, especially when it comes to illustrations derived from the Apocalypse and its Old Testament antecedents. One thinks, for example, of Umberto Eco's The Name of the Rose, in which the novice Adso experiences a terrifying vision in front of a sculpted tympanum that is clearly a pastiche of those at Moissac and Conques. Admittedly, this is not a medieval example, but many medieval apse mosaics and tympana draw on the same set of scriptural sources employed by other images discussed by Ganz.
As can be surmised from what has been said thus far, Ganz' book is a synthesis in the best sense of the word. It brings together a great deal of material, much, if not all, of which will be familiar to specialists who have worked on aspects of this rich and complex subject. Klein, Lewis, Morgan and Christe have published extensively on illustrated Apocalypses; Krüger, Schmitt and Frugoni on the representations of the stigmatization of Francis of Assisi; Caviness, Meier-Staubach and Saurma-Jeltsch, not to mention a host of others, on Hildegard of Bingen; Keller, Lentes, Largier and this author on Heinrich Seuse; Bogen and Paravicini Bagliani on medieval dream visions, and so on. In some respects, Ganz' study is at times too limited to examples or case studies that have featured prominently in previous scholarship. Given the book's admirable ambition, one would have liked to have seen more unfamiliar examples introduced to the discussion. Even a few classics are excluded. Although it may seem self-interested of this author to say so, it is difficult to understand how a book on the subject of the representation of visions in the Middle Ages includes no discussion of, let alone a reproduction from, the mystical miscellany known as the Rothschild Canticles, illuminated in French Flanders ca. 1300, which contains among the most sophisticated and certainly the most extended series of images in all of medieval art intended both to instruct the viewer and to structure experiences that, even if not visionary per se, were similar in kind.  What makes the Rothschild Canticles so interesting in this regard is that with few exceptions, its images do not illustrate or even correspond with texts that describe visionary experience. Rather, in a spectacular series of 51 full-page miniatures (originally more), it seeks to provide a simulacrum of such experience, drawing on imagery derived from the liturgy and exegesis combined in brilliant visual configurations of kaleidoscopic complexity, variety and novelty. Also excluded are the images in the fourteenth-century English compendium known as the Omne bonum, published by Lucy Freeman Sandler, which explicitly address issues and levels of vision, above all, the visio beatifica. 
To summarize: Ganz has written an admirable, if imperfect, book. Its insights are in part the product of what might be viewed as his at times one-sided emphasis on the formal analysis of complex images at the expense of closer consideration of context, however construed. On the whole, however, one has to be grateful to the author for a book that enables us for the first time to survey much of a grand narrative that has not previously been attempted on so ambitious or comprehensive a scale.
 For an introduction to some of the issues, see Cynthia Hahn: Vision, in: A Companion to Medieval Art. Romanesque and Gothic in Northern Europe, ed. by Conrad Rudolph (= Blackwell Companions to Art History; 2), Oxford 2006, 44-64.
 Early material could have been included; see, e.g., Jerzy Miziołek: 'When Our Sun is Risen'. Observations on Eschatological Visions in the Art of the First Millenium, in: Arte Christiana 82 (1994), 245-260.
 It is inevitable that some of the vast bibliography on Hildegard was overlooked, e.g., A. J. van Run: Imaginaria visione. Over kunst en visioenen in de Middeleeuwen, in: Utrechtse Bijdragen tot de Medievistik 6 (1986), 122-150.
 Bernhard Bischoff: Das biblische Thema der Reichenauer 'Visionären' Evangelisten, in: Bernhard Bischoff: Mittelalterliche Studien. Ausgewählte Aufsätze zur Schriftkunde und Literaturgeschichte, 2 vols., Stuttgart 1966-1967, vol. 2, 304-311.
 Johann Konrad Eberlein: Apparitio regis - revelatio veritatis. Studien zur Darstellung des Vorhangs in der bildenden Kunst von der Spätantike bis zum Ende des Mittelalters, Wiesbaden 1979.
 For mirror as metaphor, see Ralf Konersmann, Lebendige Spiegel. Die Metapher des Subjekts, Frankfurt 1988. For framing devices in medieval manuscripts, see Andrea von Hülsen-Esch, Der Rahmen im Rahmen der Buchmalerei, in: Format und Rahmen. Vom Mittelalter bis zur Neuzeit, ed. Hans Körner and Karl Mösender, Berlin 2008, 9-40. One of the examples discussed by Ganz, the set of Angevin Apocalypse panels in Stuttgart, has since been published by Rosemary Muir Wright, Living in the Final Countdown. The Angevin Apocalypse Panels in Stuttgart, in: Prrophecy, Apocalypse and the Day of Doom. Proceedings of the 2000 Harlaxton Symposium, ed. by Nigel Morgan, Donington 2004, 261-276.
 Owen C. Thomas: Interiority and Christian Spirituality, in: Journal of Religion 80/1 (2000), 41-60. For feminist critiques of exterior/interior distinctions; see Sarah Beckwith: Passionate Regulation. Enclosure, Ascesis and the Feminist Imaginary, in: South Atlantic Quarterly 93 (1994), 803-824; and Amy Hollywood: Sensible Ecstasy. Mysticism, Sexual Difference, and the Demands of History, Chicago 2002, esp. chap. 7.
 See, for example, for the Middle Ages, David Aers: A Whisper in the Ear of Early Modernists; Or, Reflections on Literary Critics Writing the 'History of the Subject', in: Culture and History, 1350-1600. Essays on English Communities, Identities, and Writing, ed. by David Aers, Detroit 1992, 177-202; Katherine C. Little: Confession and Resistance. Defining the Self in Late Medieval England, Notre Dame 2006; Jennifer Brian: Looking Inward. Devotional Reading and Private Self in Late Medieval England, Philadelphia 2008; and for the early modern period, Moshe Sluhovsky: Discernment of Difference, the Introspective Subject, and the Birth of Modernity, in: Journal of Medieval and Early Modern Studies 36 (2006), 169-199.
 See Jeffrey F. Hamburger: Openings, in: The Medieval Imagination, ed. by Constant Mews, Melbourne forthcoming.
 Craig Harbison: Visions and Meditations in Early Flemish Painting, in: Simiolus 15 (1985), 87-118.
 William Diebold: 'Except I shall see ... I will not believe' (John 20:25). Typology, Theology, and Historiography in an Ottonian Ivory Diptych, in: Objects, Images and the Word. Art in the Service of the Liturgy, ed. by Colum Hourihane (= Index of Christian Art. Occasional Papers; 6), Princeton 2003, 257-273.
 Kurt Ruh: Seuse, Vita c. 52 und das Gedicht und die Glosse 'Vom Überschall', in: Heinrich Seuse. Studien zum 600. Todestag 1366-1966, ed. by Ephrem M. Filthaut, Cologne 1966, 191-212.
 Michael Camille: The Gregorian Definition Revisited, in: L'image. Fonctions et usages des images dans l'Occident médiéval. Actes du 6e 'International Workshop on Medieval Societies' Centre Ettore Majorana (Erice, Sicile, 17 - 23 octobre 1992), ed. by Jérôme Baschet / Jean-Claude Schmitt, Paris 1996, 89-107.
 See, inter alia, Bernard McGinn: Visions and Critiques of Visions in Thirteenth-Century Mysticism, in: Rending the Veil. Concealment and Secrecy in the History of Religions, ed. by Elliot R. Wolfson, New York 1999, 87-112; Susan C. Karant-Nunn: Gedanken, Herz und Sinn. Die Unterdrückung der religiösen Emotionen, in: Kulturelle Reformation. Sinnformationen im Umbruch 1400-1600, ed. by Bernhard Jussen / Craig Koslofsky (= Veröffentlichungen des Max-Planck-Instituts für Geschichte; 145), Göttingen 1999, 69-95; the essays of Robert W. Scribner, among them: Vom Sakralbild zur sinnlichen Schau. Sinnliche Wahrnehmung und das Visuelle bei der Objektivierung des Frauenkörpers in Deutschland im 16. Jahrhunderts, in: Gepeinigt, begehrt, vergessen. Symbolik und Sozialbezug des Körpers im späten Mittelalter und in der frühen Neuzeit, ed. by Klaus Schreiner / Norbert Schnitzler, Paderborn 1992, 309-336; and Jeffrey F. Hamburger and Hildegard Elisabeth Keller, A Battle for Hearts and Minds. The Heart in Reformation Polemic, in: Medieval Mysticism in the Modern Age, ed. by Sally Poor, forthcoming.
 For the relationship of the homo interior and homo exterior, see Lionel J. Friedman: 'Occulta cordis', in: Romance Philology 11 (1957), 103-119; Peter von Moos: Occulta cordis. Contrôle de soi et confession au Moyen Âge, in: Médiévales 29 (1995), 131-140 and 30 (1996), 117-37; von Moos: Herzensgeheimnisse (occulta cordis). Selbstbewahrung und Selbstentblößung im Mittelalter, in: Schleier und Schwelle. Archäologie der literarischen Kommunikation. Geheimnis und Öffentlichkeit, ed. by Aleida and Jan Assmann, Munich 1997, 89-100; and, with special emphasis on Seuse, Jeffrey F. Hamburger: Visible, yet Secret. Images as Signs of Friendship in Seuse, in: Amicitia - weltlich und geistlich. Festschrift for Nigel Palmer on the Occasion of his 60th Birthday, ed. by Annette Volfing / Hans-Jochen Schiewer (= Oxford German Studies; 36/2), Oxford 2007, 141-162.
 Norbert Schnitzler: Ikonoklasmus - Bildersturm: theologischer Bilderstreit und ikonoklastisches Handeln während des 15. und 16. Jahrhunderts, Munich 1996.
 Despite citing Michael Camille: Sensations of the Page. Imaging Technologies and Medieval Illuminated Manuscripts, in: The Iconic Page in Manuscript, Book, and Digital Culture, ed. by George Bornstein / Teresa Tinkle, Ann Arbor 1998, 33-53. Among the other studies that could be cited are Bernard McGinn: The Language of Inner Experience in Christian Mysticism, in: Spiritus 1 (2001), 156-171, esp. 161. See also Gordon Rudy: Mystical Language of Sensation in the Later Middle Ages, New York 2002; Robert J. Hauck: They Saw What They Said They Saw. Sense Knowledge in Early Christian Polemic, in: Harvard Theological Review 81, no. 3 (1988), 239-249; and Clifford Davidson: Heaven's Fragrance, in: The Iconography of Heaven, ed. by Clifford Davidson (= Early Drama, Art, and Music Monograph Series; vol. 21), Kalamazoo Michigan 1994, 110-127. For the history of art, see Reindert L. Falkenburg: Smaak in beeldspraak: Een liefdesmetafoor in schilderijen van Maria met het kind uit de zuidelijke Nederlanden (1450-1550), in: Spiegel historiael 26, no. 10 (1991), 419-425; Carl Nordenfalk: The Five Senses in Late Medieval and Renaissance Art, in: Journal of the Warburg and Courtauld Institutes 48 (1985), 1-22; Elisabeth Sears: Sensory Perception and Its Metaphors in the Time of Richard of Fournival, in: Medicine and the Five Senses, ed. by William F. Bynum / Roy Porter, Cambridge 1993, 17-39; and Elizabeth Sears: The Iconography of Auditory Perception in the Early Middle Ages. On Psalm Illustration and Psalm Exegesis, in: The Second Sense. Studies in Hearing And Musical Judgement from Antiquity to the Seventheenth Century, ed. by Chales Burnett / Michael Fend / Penelope Gouk, London 1991, 19-38.
 Wolfgang Kemp: Christliche Kunst. Ihre Anfänge, ihre Strukturen, Munich 1994.
 Ganz cites Sixten Ringbom: Some pictorial conventions for the recounting of thoughts and experiences in late medieval art, in: Medieval Iconography and Narrative. A Symposium. Proceedings of the Fourth International Symposium organized by the Centre for the Study of Vernacular Literature in the Middle Ages, held at Odense University on 19-20 November, 1979, ed. by Flemming G. Andersen / Esther Nyholm, Odense 1980, 38-69. In the same vein are: Vision and Conversation in Early Netherlandish Painting. The Delft Master's 'Holy Family', in: Simiolus 19 (1989), 181-190; and: Action and Report. The Problem of Indirect Narration in the Academic Theory of Painting, in: Journal of the Warburg and Courtauld Institutes 52 (1989), 34-51.
 Victor I. Stoichità: Visionary Experience in the Golden Age of Spanish Art, London 1995.
 Erwin Panofsky: Studies in Iconology. Humanistic Themes in the Art of the Renaissance, New York 1972, 10.
 For example, Jérôme Baschet: Pourquoi élaborer des bases de données d'image? Propositions pour une iconographie seriélle, in: History and Images. Towards a New Iconology, ed. by Axel Bolvig / Phillip Lindley, Turnhout 2003, 59-106, and, too recent to have been consulted by Ganz, Jérôme Baschet: L'iconographie médiévale, Paris 2008, chapter 7 ("Inventivité et sérialité des images médiévales").
 William J. Thomas Mitchell: Iconology. Image, Text, Ideology, Chicago 1986.
 Mise en page et mise en text du livre manuscrit, ed. by Henri-Jean Martin / Jean Vezin, Paris 1990.
 Laura Kendrick: Animating the Letter. The Figurative Embodiment of Writing from Late Antiquity to the Renaissance, Columbus OH 1999.
 For Rupert of Deutz, see Rhabanus Haacke: Die Mystischen Visionen Ruperts von Deutz, in: Sapientia doctrina: Mélanges de théologie et de littérature médievales offerts à Dom Hildebrand Bascoeur O.S.B., vol. 1 (= Recherches de Théologie ancienne et médiévale; 1), Louvain 1980, 68-90; and Christel Meier-Staubach: Ruperts von Deutz literarische Sendung. Der Durchbruch eines neuen Autorbewusstseins im 12. Jahrhundert, in: Aspekte des 12. Jahrhunderts. Freisinger Kolloquium 1998, ed. by Wolfgang Haubrichs / Eckart C. Lutz / Gisela Vollmann-Profe (= Wolfram-Studien; 16), Berlin 2000, 29-52. For Hedwig, see most recently Jeffrey F. Hamburger: Representations of Reading - Reading Representations. The Female Reader from the Hedwig Codex to Châtillon's Léopoldine au Livre d'Heures, in: Die lesende Frau. Traditionen, Projektionen, Metaphern im fächer- und epochenübergreifenden Vergleich, ed. by Gabriela Signori, Wolfenbüttel 2007, 183-245.
 See Jeffrey F. Hamburger: Speculations on Speculation. Vision and Perception in the Theory and Practice of Mystical Devotions, in: Deutsche Mystik im abendländischen Zusammenhang. Neu erschlossene Texte, neue methodische Ansätze, neue theoretische Konzepte, Kolloquium Kloster Fischingen, ed. by Walter Haug / Wolfram Schneider-Lastin, Tübingen 2000, 353-408.
 Jean-Marie Sansterre: 'Omnes qui coram hac imagine genua flexerint ...'. La vénération d'images de saints et de la Vierge d'aprés les textes écrits en Angleterre du milieu du XIe aux premières décennies du XIIIe siècle, in: Cahiers de civilisation médiévale 49 (2006), 257-294; Visions et miracles en relation avec le crucifix dans des récits des Xe - XIe siècles, in: Volto santo in Europa. Culto e immagini del crocifisso nel medioevo. Atti del convegno internazionale di Engelberg (13-16 settembre 2000), ed. by Michele Camillo Ferrari / Andreas Meyer, Lucca 2005, 387-406; L'image blessée, l'image souffrante. Quelques récits de miracles entre Orient et Occident (VIe - XIIe siècle), in: Les images dans les sociétés médiévales. Pour une histoire comparée, ed. by Jean-Marie Sansterre (= Bulletin de l'Institut Historique Belge de Rome ; 69), Turnhout 1999, 113-130.
 Thomas Kren / Roger Wieck: The Visions of Tondal from the Library of Margaret of York, Malibu CA 1990; and Margaret of York, Simon Marmion, and the Visions of Tondal. Papers delivered at a symposium organized by the Department of Manuscripts of the J. Paul Getty Museum in collaboration with the Huntington Library and Art Collections, June 21-24, 1990, ed. by Thomas Kren, Malibu CA 1992.
 From the large literature on this subject, I cite only a handful of studies: Frank Bezner: Vela veritatis. Hermeneutik, Wissen und Sprache in der 'Intellectual History' des 12. Jahrhunderts (= Studien und Texte zur Geistesgeschichte des Mittelalters; 85), Leiden 2005; Michaela Krieger: Zum Problem des Illusionismus im 14. und 15. Jahrhundert - ein Deutungsversuch, in: Pantheon 54 (1996), 4-18; and Klaus Krüger: Mimesis als Bildlichkeit des Scheins. Zur Fiktionalität religiöser Bildkunst im Trecento, in: Künstlerischer Austausch - Artistic Exchange. Akten des XXVIII. Internationalen Kongresses für Kunstgeschichte Berlin, 15.-20. Juli 1992, vol. 2, ed. by Thomas W. Gaehtgens, Berlin 1993, 423-36.
 See, e.g., Michael Curschmann, Epistemological Perspectives at the Juncture of Word and Image in Medieval Books before 1300, in: Multi-Media Compositions from the Middle Ages to the Early Modern Period, ed. by Margriet Hoogvliet, Groningen Studies in Cultural Change 9, Leuven 2004, 1-26.
 See Henry Thode: Franz von Assisi und die Anfänge der Kunst der Renaissance in Italien, Berlin 1885; Anna Maria Szylin: Henry Thode (1857-1920). Leben und Werk, Frankfurt am Main 1993; and Walter Paatz: Henry Thode - einst und jetzt, in: Henry Thode 1857-1920 (= Ruperto-Carola; 8/20), Heidelberg 1956. For later iterations of the argument, see John Fleming: An Introduction to Franciscan Literature of the Middle Ages, Chicago 1977.
 Jeffrey F. Hamburger: The Place of Theology in Medieval Art History. Positions, Problems, Possibilities, in: The Mind's Eye. Art and Theological Argument in the Middle Ages, ed. by Jeffrey Hamburger / Anne-Marie Bouché, Princeton 2005, 11-31.
 See, e.g., Suzanne Conklin Akbari: Seeing through the Veil. Optical Theory and Medieval Allegory, Toronto 2004.
 Michael Camille: Before the Gaze. The Internal Senses and Late Medieval Practices of Seeing, in: Visuality Before and Beyond the Renaissance. Seeing as Others Saw, ed. by Robert S. Nelson, Cambridge 2000, 197-223.
 B. Alberti Magni, Ratisbonensis episcopi, Ordinis Praedicatorum, Opera Omnia. Vol. 24. Enarrationes in Joannem, ed. by Auguste and Emil Borgnet, Paris 1890, 44: "In mundo erat, id est, visibiliter factus in mundo. [...] Non quidem locum mutando quia ubique est, sed tantum visibilis apparens."
 Jean-Claude Schmitt: La Culture de l'Imago, in: Annales ESC 51 (1996), 3-36.
 Jeffrey F. Hamburger: The Rothschild Canticles. Art and Mysticism in Flanders and the Rhineland ca. 1300, New Haven 1990.
 Lucy Freeman Sandler: Face to Face with God. A Pictorial Image of the Beatific Vision, in: England in the Fourteenth Century. Proceedings of the 1985 Harlaxton Symposium, ed. by William M. Ormrod, Woodbridge 1986, 224-235.