Stuart Clark focuses on debates about vision, founded on philosophy but with wide ramifications for the study of everyday life, religion, and politics. Late medieval analyses of vision (and other sensory perception) had identified streams of “species”—or replications of the image—which passed from object to eye. They were then further multiplied into the brain and the memory, where they were impressed as if into wax. Cutting into the stream at any point, one would have found an exact likeness of the object. There was at the same time a close link between cognition and moral and ethical qualities: direct sensory contact, including vision, allowed qualities to pass between the object perceived and the perceiver. These were old notions, traceable to Aristotle, Plato, and Augustine. The premise of this work is that this understanding of vision changed in early modern Europe. People came to conceive of vision—and other senses—as culturally determined, deciding that perception was not the product of a clearly defined objective process. This book is about how that change came about and the theories that replaced the medieval understanding of cognition.

Clark looks especially at areas of sensory perception where comprehension of its operation had broken down. Medieval analyses had always listed the curiosities of vision, noting examples of sensory error, such as afterimages of the sun, but in early modern Europe these assumed special importance. George Hakewill's The Vanitie of the Eie, of 1608, frames the discussion in this volume; its publication came at the end of an extended period of denigration of the sense of sight, highlighting visual delusion as the cause of the evils of the world. In the early sixteenth century, the imagination, once only a single component among the body's internal senses, became the sole component interposed between external sensory perception and the spiritual soul. It gained, however, a reputation for unreliability, undermining visual perception and those institutions that depended on that perception—from religion to the state. At the same time, intellectuals gained an interest in visual deception—“prestiges” (and prestidigitation)—linked to magic. The deceits of juggling and sleight of hand were prominent in religious polemics: “lying images” and the deceptions of the mass and miracles. The moral truth that had come with medieval optics had been perverted. Magic increased the number of exceptions to the reality of sight as it had been understood in Aristotelian terms, and those exceptions might be linked to demonism and witchcraft and to blatant trickery. John Hilsey's sermon at St. Paul's Cross in 1538 exposed the Rood of Boxley, with its figure of Christ, almost a marionette, with moving eyes and lips. Deception was at the heart of confessional dispute: if sight was a form of touch, viewing the consecrated host at its elevation produced tangible benefits as one came in direct contact with this form of the holy. Vision was crucial to debates about transubstantiation, to the veneration of images and relics; if Catholicism was seen as beguiling the senses, Protestantism developed the discipline of measured control of sensory perception.

The devil was the ultimate deceiver, capable of altering the stream of species to the eyes. Whether one perceived miracles, apparitions, and witches and their works was dependent on one's religious, moral, and social status. Perceptual chaos was the logical result of the devil's intervention, and making judgments about what one had seen was fraught with both complexity and danger. What were the proofs of witchcraft, and how did one know when to believe the judgment of one's eyes? What was the proof of the Resurrection? By the eighteenth century, illusions such as raising the dead were explained in terms of mechanics, mathematics, and optics, but the seventeenth century saw a continuing debate about the nature of visual phenomena, in which some continued to argue that visual cognition was a factor of the qualities of the perceiver, a truth founded on religion. Clark turns to two further examples, Macbeth and Saul's encounter with the witch of Endor, as ways of exploring visual uncertainty. A further chapter focuses on dreams, the interpretation of which from antiquity onward was linked to the virtue of the dreamer for an assessment of their value, especially as a prognostication, rather than as a product of the dreamer's experience.

Another strand in sensory doubt led back to the Greek skeptics and Pyrrho. Here was to be found denial of links between the experience of the senses and any way of knowing about the world outside the body. Between about 1570 and the 1630s, these discussions came to the foreground of French philosophy, from Michel de Montaigne to René Descartes. The dilemma, put simply, was that there was either no way of knowing about the external world or there was, but it had to accept the fallibility of some experience. Later seventeenth-century developments tended to see sense perception as producing signs, neural messages rather than images, which formed the basis of cognition. Debates about the mismatches between perception and cognition produced by the medieval model and optics were sidelined. “By the 1670s, the old question of whether human vision gave reliable access to the real world—of whether vision was veridical—had certainly not been settled. But it had been made temporarily redundant by a new acceptance … that visual reality was not so much something grasped by human sensory perception as constructed by it” (356). This was to be the triumph of the work of Thomas Hobbes, Joseph Glanvill, Bishop George Berkeley, and others, tenets accepted by members of the Royal Society such as John Wilkins, Robert Boyle, and Isaac Newton.

This is an important book of broad scholarship, albeit one that requires close reading. Clark is to be congratulated on his wide-ranging and thought-provoking study.