The book focuses on anamorphoses, the odd perspective images that Jurgis Baltrušaitis called hallucinatory in his seminal study (Anamorphoses; ou, Perspectives curieuses [1955]) but which Arnaudo wishes to examine as technical and expressive variants of illusionism (7). Instead of interpreting these fantastical optical illusions as the absurd side of perspective, the aim of the book is to evaluate them in light of the consideration they enjoyed among sixteenth- and seventeenth-century letterati, preachers, scholars, poets, philosophers, and authors of emblem books, who often resorted to optical metaphors to explain their thoughts.

This kind of bizarre image originated in antiquity, but the term anamorphosis is relatively recent. It was invented by the most inventive scholar of Baroque illusionism and imaginary worlds, Athanasius Kirchner, in his book Ars magna lucis et umbrae (1645), to describe the transformation of an image (anamorphosis sive transformatio figurae). Arnaudo embraces Kirchner's definition, expanding it to acknowledge fully the role of the viewer: an anamorphosis is “an image that changes when the position of its viewer changes” (12). Effectively, throughout the book Arnaudo refers to anamorphoses as immagini cangianti, changing images, which, just like the more familiar colori cangianti of Renaissance and Baroque art, transform when the point of view of an observer changes.

Arnaudo does not focus on the technical aspects of anamorphosis and the different mechanisms of transformation of the image (movement of the viewer, rotation of the image, use of mirrors or lenses) or on the subject of the immagine cangiante (an undefined image, a landscape, or a face). He concentrates instead on the emotional responses that these images generated in viewers and how these responses were recorded in literary writings. Because of his interest in viewers’ emotional responses, Arnaudo is able to expand considerably the range of immagini cangianti, which include not only paintings made to be viewed exaggeratedly from the side but also such diverse representations as portraits by Arcimboldo; images generated by deforming mirrors; illusions projected in the air by concave mirrors; occasional representations formed accidentally by clouds, stains, or rocks; anthropomorphic landscapes; reflected and refracted images in the lenses of microscopes and telescopes. The title of the book, Il trionfo di Vertunno, refers, albeit cryptically, to this great variety of anamorphotic images, literally their triumph (trionfo), while Vertunno, the god of changes and transformations, refers, also cryptically, to the very nature of immagini cangianti.

Immagini cangianti abound in Renaissance and Baroque poems, plays, treatises, and sermons, a fact that Arnaudo perceptively interprets as an indication of their wide circulation among a large public. The bulk of the book is an excursus of the metaphorical use of anamorphosis in the late Cinquecento and the Seicento through the examination of six case studies taken from six different authors who resorted to immagini cangianti to explain difficult topics. The philosopher Giordano Bruno used optics to explain the infinity of his revolutionary universe. The poet Marino Marini described composite images “a la Arcimboldo” in his poems. Kircher devoted an entire treatise to optical fantasies. Emanuele Tesauro, a rhetorician and master of metaphors, referred constantly to optical metaphors in his writings, while the historian and letterato Daniello Bartoli deeply disliked anamorphoses, presenting them as the ultimate example of deceptiveness. In his analysis of these texts, Arnaudo brings to the surface the pervasive presence of anamorphosis both as a literary theme, recovering the instances in which each author pushed the reader to visualize a changing image and “to experience virtually the illusionistic spectacle,” as well as a “textual strategy that incorporates the characteristics and effects of these optical illusions” (17).

The merit of Arnaudo's book is to have successfully switched the focus from the techniques of anamorphosis to the emotional responses that they generate. While the book is full of insight, one wished the author had pushed his argument and approach to their full potential. While interested in the discrepancy between techniques and responses, he is less aware of the stimulating work of historians of science and of art, who have investigated the deep connections between viewers’ specific emotional responses and the materiality and techniques of images and texts. Similarly, his concentration on responses to anamorphosis is commendable, but it might have gained a broader perspective had it been more fully connected to the physicality of a moving subject, which, as Arnaudo acknowledges, is the sine qua non of an immagine cangiante. Modern studies in phenomenological philosophy and cognitive sciences would have added a very important perspective to the reception and emotional responses to these famous illusions that dazzle modern viewers just as they did Renaissance and Baroque observers and readers.