How welcome it is to read a book, manifestly about fin-de-siècle Symbolism, whose ambitions are to parse communication itself. Andrei Pop’s A Forest of Symbols: Art, Science, and Truth in the Long Nineteenth Century traces allied concerns among artists, scientists, philosophers, and mathematicians about the incommensurability of private thought and public expression and the symbol as an agent within those realms. The book argues that Symbolism arose from crises of confidence in knowledge production in Western philosophy and the sciences. While this is not a new claim, the insight that Pop offers is that Symbolism may be understood as a self-critical phenomenon that explored the instability of private and public languages. He traces inter- and multidisciplinary inquiries into how and if subjectivity can be imaged, how and if symbols operate as communication, how and if an audience makes sense of the symbol, and what that symbol, perhaps, stands for in regard to “truth.” He further proposes that Symbolist thought, whether manifested through language or the visual arts, is neither incomprehensible nor disunited, but may be understood as a form of logic.

The book’s “plan” is to “chart how meaning is made” (49), how mind, world, and image correspond. Drawing its title from Charles Baudelaire’s “Correspondances” (1857), the book is organized into five chapters and a critical conclusion, each focusing on one or more central projects that build Pop’s thesis. The first chapter, “Symbolisms in the Plural,” lays out the paradox of objective versus subjective experience, reading into canonical texts by, among others, Stéphane Mallarmé and G.-Albert Aurier. Pop traces and critiques psychologism—psychology as an explanatory practice in a wide variety of phenomena in the later nineteenth century—and the ways in which the emphasis on human cognition “leaves the subject more mysterious than ever” (31). Within this arena, Pop explores the increasing attention across disciplines to private experience and the complex problem of enlisting the senses as a means of registering and explicating private, inchoate thought. Here he recasts a well-worn schism between Impressionism (as an art of sensation) and Symbolism (as a pathway to interiority) by enlisting corollary concerns in mathematics and physics inter alia Hermann von Helmholtz, Ernst Mach, and Gottlob Frege, who grappled with the challenge of devising symbols as devices to point to realities outside of tangible, sensorial “truths.” Introducing “arithmatic psychologism,” Pop makes a productive claim to the tethering of Aurier and his cohorts to rhetorical structures of logic. The highwire act of A Forest of Symbols is to reintegrate Symbolism with the problem of the self as mediated through sense impressions, experimental science, and analytic philosophy. How can a symbol offer palpability without concreteness? With such a question, Pop emphasizes Symbolism as a pivot point, and not a strange waystation, in the history of modernism.

The second chapter, “Crises of Sense: The French Take on Edgar Allan Poe,” queries whether there is a “Symbolist method in the arts” (49). Probing Poe’s The Raven, Mallarmé’s translation of the text, and Édouard Manet’s 1875 illustrations to Richard Lesclide’s deluxe edition of it, Pop queries how private experience “flickers from one mind to another” (90). Poe’s 1846 exegesis of the poem offers Pop a scaffold from which to consider how the contributors to the French publication each embedded a specific mood in the mind of the reader and embedded himself into the text. Pop focuses on Manet’s image of an empty chair amid shadows scrawled across the page as a corollary to the mood-text. The problem of intelligibility entrenched in the poem, the translation, and Manet’s images offers “not a private language in the singular, the shared lingua franca of thought, but private languages, or better yet private language as a mass term, the possibility of complex aesthetic experience articulated by each person” (97, emphasis in original). The experiences of the private, a “mass” private, the public, and the aesthetic in turn open potential chasms of misunderstanding.

Chapter 3, “Where Do We Come From? Symbolism’s Psychologic Roots,” tackles the problem of “doubling,” the unstable coexistence of outer world and inner experience. Color perception is at the heart of this chapter as an arena in which sense perception, subjectivity, and the communication of color understanding are indeterminate and perhaps incommensurate. Pop also traces how new optical technologies that “promise[d] making visible the very act of seeing” (111) paradoxically troubled any notion of objectivity: “An analysis of optics, or of light, could not itself bridge this divide, because pictures are not perceptions but are themselves perceived, thus multiplying whatever effects of the real world they are supposed to have successfully incorporated” (126). The “doubling problem” Pop offers (49, 135) was addressed by printmakers such as Félix Bracquemond and Mary Cassatt, whose tactility articulated the tensions between sense perception and subjectivity.

Chapter 4, “What Are We? A Symbolist Picture Theory,” historicizes cross-disciplinary attempts to graphically render first-person perceptual experience. Here Pop enlists the work of Austrian physicist and perceptual psychologist Ernst Mach, whose much discussed rendering of his reclining body as framed by his left orbital lobe is examined in detail. Pop’s assertion of a Symbolist picture theory is grounded in such an analytical overloading of the sensorium: “Can the sensible signs of another’s consciousness serve as vehicles of their own?” (142). To see through Mach’s left eye is to map the self onto the image and also to experience the paradox of being and not being present in it. The rupture between Impressionism and Symbolism—observing and imagining, according to Pop’s argument—is thematized here.

In this chapter and throughout the book, Pop brings into conversation the Jena-based philosopher and mathematician Friedrich Ludwig Gottlob Frege (1848–1925), a mentor to Ludwig Wittgenstein (Frege’s entry in the index is by far the longest). In fact, much of the book turns on Frege’s philosophy of language as grounded in logic and mathematics, and on Frege’s notion of the sign as any expression enlisted to designate an object. Pop’s integration of the early roots of predicate calculus and analytic philosophy into a larger theory of Symbolist practice is novel and therefore deserves special attention.

Names, Frege offered, are objectively denotative and appeal to thought, and are therefore both concrete and subjective. “Odysseus,” for example, concretely refers to a person and to a concept—a person who may or may not have existed. Signs are therefore about the “sense” of something as well as the “truth” of the thing. Frege’s writings are particularly inspiring to Pop as a means of teasing out central concerns of Symbolist practice, of meaning making as both logical and reliant on the collaboration of subjectivities: “the force of assertion does not lie in any subject or object, but in the context shared by creator and recipient” (165). Frege invented a nearly incomprehensible visual sign system, published in 1879 as Begriffsschrift (Concept notation)—which Pop terms “radical pictoriality”—to communicate mathematical and linguistic proofs (169). Pop reads this system of symbols with which Frege attempted to construct logical sentences as a “symbolist picture theory.” By “[bringing] out the formal structure of picturing,” Frege’s techniques “result not in a transfigured, unrecognizable world, but in a conceptually clarified one” (175, 178). In Pop’s work, Frege’s application of logic to mathematics and to the linguistic dimensions of picture making was both corollary to and interwoven with contemporaneous efforts to comprehend imagination in relation to the senses. I am left pondering whether such work forecloses the complex relationalism that Pop explores elsewhere.

It must be said that some of the claims made by A Forest of Symbols would have benefited from a clearer engagement with important publications about the entanglement of Symbolism with the sciences around 1900. Alliances and arguments with Barbara Larson’s The Dark Side of Nature (Penn State University Press, 2005), Robert Brain’s The Pulse of Modernism (University of Washington Press, 2015), Allison Morehead’s Nature’s Experiments and the Search for Symbolist Form (Penn State University Press, 2017), and Michelle Facos and Thor Mednick’s anthology The Symbolist Roots of Modern Art (Routledge, 2015), among others, might have offered a platform for dispensing with the old canard that Symbolism was a reaction to empiricism (whether occultist or academic). It is also helpful to read Pop’s book through Linda Dalrymple Henderson’s foundational The Fourth Dimension and Non-Euclidean Geometry in Modern Art (Princeton University Press, 1983; expanded ed., MIT Press, 2013) to reenlist the permeability of empirical sciences and esoterism in the discussion of private versus public languages.

Finally, more grounding would be helpful to situate Pop’s assertion that the intellectual crises of the nineteenth century accord with what he terms our contemporary “tribalism” in the humanities. The book opens with that claim (31) and concludes with skepticism toward both social history and reception studies (237–38). A Forest of Symbols posits that argumentation itself is crucial: “To engage with pictures intensely is not merely to perceive, but to think about and argue about them” (238). This book offers a rewarding arena for such contestation of meaning. Pop’s confrontation with and around Symbolism is important, as is his ”sobering reminder of the difficulty of the Symbolist enterprise, of the fact that understanding how an image works, and how the mind works, is . . . grinding and unfinished, perhaps in the end unfinishable work” (185, emphasis in original).