Helen Keller, the American author and activist who was left blind and deaf from an early illness, is a central and paradoxical figure in Ackerman’s exploration of the senses. Instead of representing sensory deprivation, Keller is a “prodigy” of perception, proof of the power of the senses that remained to her. Ackerman repeatedly invokes Keller to illustrate how exquisitely attuned a person can become to the world, especially through smell and touch.

Ackerman highlights Keller’s extraordinary ability to discern information that most people overlook. For example, she could identify people’s professions by the odors clinging to their clothes and could feel an approaching storm through a “throb of expectancy” in her nostrils (44). By “hearing” music through the vibrations in a radio or feeling a singer’s performance by touching his throat, Keller demonstrates that sensory experience is not confined to its primary organ. Her life becomes Ackerman’s most compelling evidence that the senses are deeply interconnected and that a reduction in some can lead to a heightened awareness in others.

Ultimately, Keller represents the book’s core theme: that a rich and sensuous life is available to anyone willing to pay attention. Ackerman uses Keller’s dramatic description of smell as the “fallen angel” of the senses to underscore its primal, emotional power. Keller’s example challenges the conventional hierarchy of the senses, proving that a full experience of life is not dependent on sight or hearing but on a deep, cultivated engagement with the world through every available channel.

The last pharaoh of Egypt, Cleopatra, is presented by Ackerman as the historical archetype of sensory mastery, particularly in the realm of smell. She is “the quintessential devotee of perfume” (59), employing scent as a sophisticated instrument of power, seduction, and political theater. Ackerman uses her as a benchmark for understanding the cultural and personal significance of fragrance in the ancient world.

Ackerman focuses on Cleopatra’s legendary encounters, such as her meeting with Mark Antony, to illustrate the sheer scale of her sensory extravagance. The detail of her perfumed sails, which announced her arrival before she was even seen, demonstrates a strategic use of scent to create an unforgettable, almost mythical presence. Other details, like anointing her hands with rose oil, scenting her feet with a lotion of cinnamon and orange blossoms, and having her bedroom floor covered in a foot and a half of rose petals, portray a life lived in a constant state of sensual indulgence.

By detailing Cleopatra’s practices, Ackerman establishes a historical precedent for the human obsession with scent. Cleopatra’s world, where perfumes were integral to religion, beauty, and diplomacy, is a vivid contrast to the modern era, where smell is often considered a secondary, almost vestigial sense. Cleopatra embodies the idea that the senses, when artfully deployed, are powerful tools for shaping perception and influencing others.

Anthelme Brillat-Savarin was a French lawyer, politician, and epicure whose 1825 book, The Physiology of Taste, remains a foundational text on the philosophy of food. Ackerman uses his witty and insightful aphorisms to frame her discussion of taste as “the social sense.” Brillat-Savarin provides a historical voice of authority that elevates eating from a biological necessity to an art form with complex social, cultural, and psychological dimensions. 

Ackerman draws on Brillat-Savarin’s work to explore the complex connections between food, society, and identity. His pronouncements, such as his famous line, “Tell me what you eat, and I shall tell you what you are” (164), help Ackerman argue that taste is a deeply personal and revealing sense. She cites his observations on how social gatherings from business deals to love affairs revolve around the table, reinforcing the idea that “breaking bread” is a fundamental act of human connection. 

By including Brillat-Savarin, Ackerman connects her contemporary exploration of taste to a long tradition of gastronomic philosophy. He represents the “sensuist” of a bygone era, a figure who understood that the pleasures of the table are intertwined with all other aspects of a rich and satisfying life.

Dr. Richard Cytowič is an American neurologist and the author of several books on the neurology of perception, including Synesthesia: A Union of the Senses (2002), which established a physiological basis for the phenomenon of synesthesia, showing that it was a real mode of perception and not, as was previously supposed, only a metaphor or literary flourish. Cytowič followed up the academic success of Synesthesia with a second book on the same subject for general audiences: The Man Who Tasted Shapes (1993). This book was a commercial success, driving an expansion of popular interest in synesthesia in the 1990s and beyond. 

For Ackerman, Cytowič’s work is crucial to her own arguments about The Interconnectedness of the Senses and her broader thesis that sense perception is a link between modern humans and our most distant evolutionary origins. Cytowič theorizes that synesthetic perceptions bypass the cerebral cortex (the part of the brain dedicated to complex thought) and are processed instead in the more evolutionarily “primitive” limbic system—suggesting that synesthesia can be seen as, in Cytowič’s own words, “a memory of how early mammals saw, heard, smelled, tasted and touched” (290).

The Russian American novelist Vladimir Nabokov, acclaimed for his complex prose and linguistic play, appears in the book as a prime literary example of synesthesia, the blending of sensory experiences. Ackerman uses his detailed, autobiographical accounts to give a vivid, first-person illustration of this rare neurological phenomenon, transforming an abstract concept into a tangible reality for the reader.

Ackerman focuses on Nabokov’s “colored hearing,” quoting directly from his memoir, Speak, Memory, where he describes the specific colors he associates with the letters of the alphabet. For instance, he explains that the long a of English has “the tint of weathered wood” (291), while a French a evokes “polished ebony” (291). This precise and personal testimony serves as Ackerman’s primary evidence for how synesthetes experience the world, not as a confusing jumble but as an ordered, if unconventional, system of cross-sensory correspondences.

Nabokov’s purpose in the text is to personify the creative potential of unusual perception. His case demonstrates that what might be considered a neurological anomaly can also be a source of artistic insight. By presenting his experience, Ackerman reinforces her theme that our sensory worlds are highly individual and that artists, in particular, may draw their unique vision from a way of perceiving that differs fundamentally from the norm. Nabokov stands as an example of how the “leaking and drafts” between the senses can fuel an extraordinary imagination (293).