The first discourse of transformation adduced by Bynum is the poetry inspired by Ovid's Metamorphoses, which was very much in vogue in the twelfth century. The Ovid of the twelfth century, she shows, was a scientist, a metaphorical cosmologist, whose poetry of transformation was read as a celebration of continuity in which transformation is less change than the unfolding of a nature; a revelation of what is, rather than a mutation of one thing into another. In the late twelfth-century commentary of Arnulf of Orleans, for example, the tale of the transformation of the youth Cyparissus--who, because of his immoderate mourning, was turned into the mournful cypress tree--becomes merely a metaphor of the aging of a handsome youth into an old man. For twelfth-century readers, the Metamorphoses was not about metamorphosis at all, but about change as fertility and generation, or else a return to one's true nature.

Bynum then turns to the learned theologians of the next century, as they wrestle with the transformations implied in the magical, the marvelous, and the miraculous. What, they ask, is the ontological basis of change brought about by miracles? When Jesus multiplied the loaves and the fishes, did he create new bread matter? When demons or angels appear in human form, have they been changed into bodies, are they "clothed" in bodies, or do they simply create the illusion of bodies? And, most famously, how was one to understand the miraculous appearance of flesh and blood that was occasionally reported to suddenly become visible in the eucharistic bread and wine?

The answer, in all but the final case, was again a discourse that attempted to control change, to limit it and to mitigate it. Miracles of transformation tended to maintain the similarity of the before and the after. Armed with Aristotelian notions of hylomorphism, of matter and form, Thomas Aquinas and other schoolmen eschewed the creation of new matter or the literal transformation of one being into another. The multiplication of the loaves was accomplished by adding extraneous pre-existing matter to the loaves, in the way that grain grows into a harvest. Demons cannot become bodies, though they can enter existing bodies (dead or alive) and animate them. Only in the transformation of bread and wine into flesh and blood does one encounter true metamorphosis, but this is the limiting case. As for the miraculous appearance of flesh and blood, this is no metamorphosis either, but the rare and terrible revelation of the accidents (the physical appearances) being brought into accord with substance.

The most flamboyant medieval discourse, and one that exercises Bynum, concerns werewolves. Twelfth-century and some thirteenth-century authors of what she broadly calls entertainment literature were fascinated not with miracles but with marvels, particularly those involving fairies, shape-changers, and transformations. These creatures emerge from popular folklore; but since their tales are told by educated clerics such as Gerald, they, too, become the object of reflection on identity and change. Gerald tells of a priest traveling from Ulster to Meath who camped for the night in a wood. He was approached by a talking wolf. The wolf bore little resemblance to the bloodthirsty monsters of classical literature or modern horror movies. Instead it politely implored the startled priest to hurry to administer the Eucharist to its dying mate, explaining that both were humans condemned by a vindictive saint to become wolves every seven years.

But once again these werewolves disappoint as stories of metempsychosis. Medieval werewolves were not humans transformed into wolves or wolves into humans. They were humans, human bodies, trapped inside the flesh and the skin of wolves. The dénouement of these stories is quite literal. When the priest hesitated to give the sacrament to an animal, its mate "pulled all of the skin off the she-wolf from the head down to the navel ... and immediately the shape of an old woman, clear to be seen, appeared." The outer wolf is stripped away, revealing the naked person, the human body, within. Once more, continuity triumphs over change.

Werewolves were but one type of monstrous hybrid. Bernard of Clairvaux, who famously railed against the depiction of those dazzling hybrid creatures that inhabited the margins of manuscripts ("monstrous centaurs, creatures part man and part beast ... many bodies with one head and many heads with one body, tail of serpent on quadruped, head of quadruped on fish"), worried even more about the monster that he saw himself and many of his contemporaries to be. Bernard longed for unity and simplicity: mixtures were usually negative, a confusion that denigrated and distracted. He was acutely aware of his own inadequacies in this regard. "I am a sort of modern chimera, neither cleric nor layman," he confessed, in an acknowledgment of his confused life of vigorous polemical engagement with the world while as a monk he was vowed to, and longed for, withdrawal and contemplation.

Hybrids, in Bernard's view, were almost always negative. They never resulted in a synthesis into something new, but instead maintained an unnatural duality. Bernard's disparagement of hybrids, as Bynum explains, was owed in part to the fact that when it came to understanding the possibility of change, of the union of two different natures into a new and better unity, Bernard was conceptually challenged. Such change was simply beyond his thought-world. Change might mean replacement, and it might mean destruction, but it could not mean becoming.

And yet Bernard was aware that Christ, the God-man, was a mixture, and so was his virgin mother. Hybridity could, then, be positive--but it was always troubling, always mysterious. And hybridity was exactly the human condition. Bernard's human was not a soul trapped in a body; it was an uneasy hybrid of body and soul, a body that was at once vile slime and humanity's only access to experience, to sensation, to ultimate joy; a soul that was both the image of God and the site of greed and despair. Since he could not really conceive of change, of merger, of becoming, Bernard's static understanding of human nature, and more generally of the world, remained a picture of unresolved mixtures forced into unities, but unities always threatening to dissolve, always tinged with horror and wonder. "For joined together to each other are God and human, mother and virgin, faith and the human heart," he wrote. "Wonderful are these mixtures, and more marvelous than any miracle, for so diverse and even so opposed to each other, they were joined together."

So how does following Bernard of Clairvaux's tortured medieval reflections on unity and mixture, stunted and limited by his scientific and conceptual tools, help us to understand our own concerns about identity and change? Aren't he and his contemporaries trapped in the particularities of their world, a world so radically different from ours that we can visit it only as aliens, not as interlocutors? Bynum offers two answers, one specific to the problem of identity and change, one more generally applicable to the historical enterprise.

About the question of change, she argues that we share with medievals ontological anxieties about the continuity of identity through transformation, however differently we may express these anxieties or attempt to resolve them: "Despite the obvious contrast between ancient and modern embrace of the shape-shifting motif, on the one hand, and medieval resistance to it, on the other, stories in the European werewolf tradition are not fundamentally contradictory: all imagine a world characterized by both flux and permanence; all confront both the promise and the horror of change." More specifically, Bynum contends that the exploration of medieval discussions of change takes us into a world of rhetorical and philosophical reflection that is sophisticated and enticing even if it is also alien. These discussions, she contends persuasively, force us to look with equal attention (and perhaps with skepticism) at our popular and learned attempts to come to terms with a yearning for a stable identity in the face of growth, decay, and death.

Bynum's more general answer to the question about the relevance of the medieval intellectual universe may be found in her first essay on wonder. Medievals, she abundantly demonstrates throughout these essays, did not resolve the problem of continuity and change even to their own satisfaction. The process of something becoming something else, or seeming to do so, reached beyond their ability to comprehend and explain; and such marvels as werewolves, hybrids, and miracles, for all their tortured reflections, remained the object of admiration and amazement and wonder rather than simply of appropriation and analysis and generalization. It is this respectful and even awed attitude toward the other that Bynum wishes to offer as the particular lesson in humility that we can derive from taking seriously the strivings of a world so distant from our own.

Whenever historians try to reduce the past to the familiar as a precursor of the present, or attempt to appropriate the past to their contemporary agendas, they are guilty of a hubris that slights the past and impoverishes the present. Bernard of Clairvaux does not hold the answer to the question of continuity and change. Nor do we get to the bottom of Gerald of Wales's fascination with werewolves when we attribute it to his unresolved psycho-sexual anxieties. Bynum wants historians to approach the past with modesty, respecting its intricacies and hesitating before claiming to have resolved its complexities. "We write the best history when the specificity, the novelty, the awe-fulness, of what our sources render up bowls us over with its complexity and its significance," she wisely remarks. "Our research is better when we move only cautiously to understanding, when fear that we may appropriate the `other' leads us not so much to writing about ourselves and our fears as to crafting our stories with attentive, wondering care."

If medieval monsters were marvels that were incomprehensible and yet significant, Bynum asks that we consider adopting a similar attitude toward the past itself. The past is not to be bought up, strip-mined, and sold off like some West Virginian coal mine. It is always more than whatever social scientists, political ideologues, and social activists desire it to be. Bynum is asking that even while we deploy all the tricks and the tools of modern historical analysis, we take seriously the obligation to marvel at the complexity, at the otherness, of the medieval world, a world that we will never perfectly understand and yet that seems to point to something worth understanding. This indeed is a monstrous challenge.