This book professes to be about nothing, but it actually deals with something important, if heretofore widely neglected: the deliberately blank spaces, erasures, and artificially enlarged voids in late medieval European arts, especially illuminated manuscripts. Gertsman asserts, in engaging prose, that these fecund spaces of emptiness were meant to be filled in by a reader's active imagination, informed by contemporary developments in theology, philosophy, and natural sciences. She focuses especially on the medium of parchment and its potential—as skin itself—to connote wounded flesh. The potency of absence in contemporary art is evident to anyone who has seen the 9/11 memorial in New York, but Gertsman shows that the exploration of emptiness usually associated with mid-twentieth-century and later art had ample medieval precedent.Gertsman finds absence pregnant with and productive of meaning. She analyzes the thirteenth-century surge in Creation imagery despite the evident challenge of representing the moment just before God created the world ex nihilo. She zeroes in on Europeans’ fear of the cipher zero and affirms a connection with apophatic theology. She shows how empty images in the fourteenth century prompted meditation and in the fifteenth century could be piously erased. She pokes at accidental and intentional penetrations of parchment. She does almost everything possible with her many nothings, and she argues that medieval readers/ viewers were similarly engaged.One term that surprises by its absence from Gertsman's book is iconoclasm (although iconoclastic does appear twice in the text). Presumably she did not find it a useful term within the chronological and geographic parameters defined in the book. Yet it might have been fruitful to consider this earlier (and also later) arena of absence. In many historical cases images were indeed “broken”—the literal meaning of the Greek term—to the point of elimination, including images of the incarnate God, but in others the traces were still eminently visible. One thinks, for instance, of the members of Theoderic's court in the sixth-century nave mosaic at Sant'Apollinare Nuovo in Ravenna: their bodies have been replaced by fictive curtains, but their hands and forearms still stand out, ghostlike, against the intervening white columns. Their bodily absence makes them more present—a precedent for Gertsman's later manuscript examples (“Erasure only works when something remains”). The case of Hagia Sophia in Constantinople (not quite effaced by Istanbul) is also intriguing. In the apse, the ninth-century mosaic of the Virgin and Child is now veiled from view in the church's recent reincarnation as a mosque. Veiling was a potent means of temporary erasure in both “Eastern” and “Western” medieval arts, a practice not addressed by Gertsman, but it was never part of Islamic practice until now.Gertsman's book fills a lacuna we did not even know we had. Scholars will surely identify more such paradoxical spaces and, like medieval readers before them, will fill them with interpretive brio.