The Book of Eels

What do you do when explanation fails—when everything you know about the world’s logic collapses in front of something you can neither measure nor fully understand? This is the question that shapes The Book of Eels by Patrik Svensson, a lyrical, philosophical, and partly scientific exploration of humanity’s struggle to comprehend one of nature’s strangest creatures—the eel. Svensson asks why, over millennia, humans have been simultaneously captivated and disturbed by this slippery, secretive fish, and why its mystery continues to mirror our own.

At the heart of Svensson’s book is a paradox: despite centuries of scientific investigation—from Aristotle’s theories of “mud-born eels” to Sigmund Freud’s frustrated search for their sexual organs—the eel remains largely unknown. It reproduces in one single, unreachable place on Earth—the Sargasso Sea—and no one has ever witnessed it mating. This enduring enigma becomes a lens through which Svensson examines science, myth, religion, memory, and identity. The eel’s mystery proves inseparable from the question of what makes us human.

The Eel as Mirror of Human Curiosity

Svensson builds his narrative around the “eel question,” a phrase scientists have used for centuries: Where does the eel come from? How does it reproduce? What does it mean that it can survive both salt and fresh water, and even crawl across land? For Aristotle, it was born from mud—an example of spontaneous generation. For Freud, in a Trieste laboratory in 1876, finding its testes became a metaphor for his own future explorations into human sexuality and repression. Each of these thinkers embodies the human yearning to impose reason on mystery. Through them, Svensson defines curiosity as both our greatest strength and our deepest torment—the unseen current driving all discovery.

Like the eel’s long voyage home to the Sargasso Sea, our pursuit of knowledge is a migration against currents we barely understand. Science keeps promising that truth will appear under the microscope, yet the eel’s secrecy resists complete comprehension. This resistance becomes a kind of faith test—a reminder that knowing has limits, and mystery may be essential for meaning.

A Personal Journey Beneath the Surface

Beyond the scientific narrative, Svensson’s story is deeply personal. He recounts nights fishing for eel with his father in southern Sweden, the smell of mud and tar, the quiet communion that required no words. For him, these moments anchor memory; they become a ritual of connection between generations. His father’s approach to fishing—patient, humble, and deeply respectful—mirrors the qualities needed to confront mystery itself. Years later, as his father falls ill and dies, Svensson realizes the eel was never just a fish but a symbol of origin, metamorphosis, and return—a living metaphor for mortality and belonging.

His storytelling oscillates between the scientific and the intimate, between laboratory and riverbank. The eel’s elusive metamorphosis—glass eel, yellow eel, silver eel—echoes the transformations in human life, from innocence to age, growth to departure. Like the eel, which always seems on its way “home” yet never fully arrives, the relationship between father and son becomes a meditation on where we come from and where we end up. Svensson suggests that origins matter not only for understanding creatures, but also for understanding love and loss.

Myth, Faith, and the Limits of Knowledge

Throughout history, humanity has viewed the eel through lenses of religion and art. In ancient Egypt, it was sacred yet feared. In Christianity, it was excluded from the symbolism of fish because of its serpentine body—an “unclean” creature without recognizable scales. Svensson shows how such moral discomfort mirrors our fear of the unknown itself: the eel’s uncanny presence reveals how we respond to what we cannot classify. In literature, from Günter Grass’s The Tin Drum to Graham Swift’s Waterland, the eel slithers between realms of life and death, sexuality and secrecy, often becoming a metaphor for truth escaping definition.

Philosophically, this discomfort leads Svensson to Freud’s concept of the “uncanny”—the tension between the familiar and unfamiliar. The eel evokes unease precisely because it reminds us of ourselves. It looks almost alive even after death; it hides where sight ends. It is both kin and stranger. For Svensson, accepting this uncanny duality—the coexistence of knowledge and mystery—is essential because the “truth” of the eel, like the truth of life, is not only empirical but emotional.

Why the Eel Matters

Ultimately, The Book of Eels claims that the eel’s survival—its mysterious existence and uncertain future—reflects the fate of human curiosity itself. The eel is now dying out; climate change, parasites, pollution, and dams have broken its migration routes. As Johannes Schmidt once spent two decades at sea to find the eel’s birthplace in the Sargasso, modern scientists rush to save it before it vanishes entirely. But Svensson warns that to preserve the eel merely as data would be a tragedy. What we must rescue is not only the species but the mystery it holds—the sense that not all truths can be measured, and not all journeys end in explanation.

Through this haunting mixture of storytelling and reflection, Svensson invites you to look at the eel—and yourself—with humility. Knowledge may tell you how things are born, but mystery reminds you why you care. In the end, the eel becomes an emblem of both what we seek to understand and what we must learn to accept: that life’s deepest truths often slither beyond the light, waiting patiently in the dark.

Patrik Svensson begins by returning to Aristotle—the origin point of both zoology and ignorance. Aristotle was fascinated by eels but failed to find their reproductive organs. From his careful dissections, he concluded that eels had neither male nor female parts. They seemed to arise spontaneously from the sea’s mud after rain—a miracle of nature that violated reason itself. This was his explanation of life emerging from nothing.

The Birth of the “Eel Question”

Aristotle’s assumption became the world’s first eel theory. For centuries, natural philosophers—Pliny the Elder, Francesco Redi, Linnaeus—would either challenge or echo him. Yet even as scientific instruments improved, the eel remained largely impenetrable. Svensson calls this enduring enigma “the eel question”: a symbol of the limits of human observation. Aristotle forged modern science’s commitment to empiricism—truth proven through perception and experience—but the eel proved that even the best methods can fail when faced with complexity.

Mud as Metaphor

Aristotle’s belief that life could spring from mud reflected more than scientific error—it was a philosophical stance. Mud, the primal soup of existence, represented the tension between life and death, creation and decay. Svensson ties this idea to humanity’s broader inclination toward metaphysics: our need to believe that something divine animates matter. When the eel appeared from mud, Aristotle saw a small reenactment of the universe’s creation—a mystery so vast that even modern science can’t fully dismiss it.

Faith and Observation

The eel’s refusal to conform pushed science beyond its own boundaries. For Svensson, Aristotle’s legacy is twofold: he gave us the method of knowledge and the awareness of its limits. When facts fail, faith begins—not religious belief, but a humbler acceptance that the world may remain unknown. The eel stands at that intersection, slippery between reason and mystery.

Key Insight

Aristotle’s mud-born eel reminds you that not all questions can be answered by observation alone. Sometimes, the persistence of wonder becomes its own kind of knowledge.

When Sigmund Freud arrived in Trieste to dissect eels, he thought he was studying biology. In truth, Svensson suggests, Freud was peering into the origins of human mystery itself. At nineteen, Freud dissected four hundred eels trying to find their testicles—symbols of reproduction, sexuality, and origin. He never succeeded. He left Trieste without finding the eel’s sex, unknowingly transforming his failure into a metaphor for the hidden regions of the human psyche.

The Scientist Meets the Symbol

Svensson delights in the irony. Freud, who would pioneer theories of repression, desire, and castration anxiety, first confronted mystery when the eel hid its sexuality from him. The young scientist’s dream of pure observation gave way to frustration, the same frustration that would define psychoanalysis: that truth lies buried beneath consciousness. Unable to find the eel’s organs, Freud turned his gaze inward—from dissecting eels to dissecting minds.

The Eel as Unheimlich

Later in life, Freud defined the “uncanny” (unheimlich) as something both familiar and foreign, something that reveals strangeness within the known. Svensson connects this concept directly back to Freud’s eel. The creature’s slimy, serpentine body—alive yet inexplicable—embodies what disturbs us about life’s hidden forces. Like the human unconscious, it moves in darkness, immune to logic. From Aristotle’s mud to Freud’s microscope, the eel remained both seen and unseen, a mirror for everything unspoken.

From Science to Symbol

For Svensson, Freud’s failed eel experiment shows how science inevitably turns into narrative. When faced with the inexplicable, we create stories to fill the void. The eel, in Freud’s case, became a story of sex, repression, and the blindness of intellect. What’s uncanny about the eel is what’s uncanny about us: our refusal to remain transparent even to ourselves.

Freud’s Lesson

The moment knowledge meets mystery—when science turns into metaphor—something new is born. As Freud learned in the lab, you can’t separate curiosity from emotion; to understand others, you must first confront your own depths.

Johannes Schmidt’s story reads like an epic of obsession. In 1904, the young Danish marine biologist set sail to solve the eel question once and for all: Where does it breed? His voyage lasted nearly twenty years. What he found—and what he failed to find—became one of science’s greatest odysseys.

The Long Voyage to the Unknown

Armed with trawls and microscopes, Schmidt crossed the Atlantic again and again, collecting thousands of tiny transparent larvae—willow leaf–shaped creatures called leptocephali. He measured their size across locations, reasoning that smaller larvae must be closer to their birthplace. Decade after decade, his specimens led him west. Finally, in 1923, he concluded that all eels originate in the Sargasso Sea, a vast patch of ocean near the Caribbean surrounded by swirling currents. He found the birthplace, though never witnessed the act itself—no one ever saw eels mating or dying there.

The Human Echo

Svensson sees Schmidt’s voyage not only as scientific discovery but as existential metaphor. Like the eels migrating thousands of miles home to die, Schmidt dedicated his life to tracing origins he could never reach. His journals read like scripture: “We know now the destination sought,” he wrote, but his knowing was built on faith. Svensson suggests that Schmidt was searching not just for the eel’s birthplace but for his own—a link to meaning lost in the currents of time and mortality.

The Unfinished Map

By the time Schmidt confirmed the Sargasso Sea as the eel’s breeding ground, he had demonstrated science’s paradox. Discovery often deepens mystery. Even now, no one has seen a mature eel in the Sargasso. The greatest answers remain qualified: “It can be assumed,” “It is probable.” Svensson uses that uncertainty to remind you that knowledge doesn’t conquer wonder—it enlarges it.

Human Migration

Like the eel, you move through life searching for origins that may never be visible. Schmidt’s endless voyage becomes a quiet metaphor for every journey home—to self, to meaning, to peace.

Throughout Svensson’s narrative, the eel stands as a challenge to how we know the world. Its refusal to conform to empirical logic forces you to consider whether full understanding is even desirable. From Aristotle’s mud to Johannes Schmidt’s Sargasso charts, knowledge about the eel grows, but so does uncertainty. Svensson argues that this tension—the coexistence of fact and mystery—is vital to our relationship with nature.

Science’s Faith Problem

Every scientific advance in the eel’s story comes with an act of belief. Schmidt “believes” his larvae point west. Freud “believes” meaning hides in what we repress. Carson “believes” the eel can teach empathy. Even the modern biologists tracking migrating eels with microchips rely on faith that their instruments tell truth. Svensson shows that science itself operates like religion—a structured faith in observation. The eel’s elusive nature symbolizes the humility science must maintain when faced with complexity larger than its tools.

Mystery as Survival

In the modern world, mystery is often seen as error, something to eliminate. But Svensson cautions that mystery may be essential for balance. Rachel Carson found joy in the unknown: eels leaving the marshes, “passing from human sight and almost from human knowledge.” Their disappearance is a kind of grace. In losing sight, we gain awe. If all mysteries were solved, he warns, the world might lose its soul.

The Human Parallel

Svensson personalizes this theme through his father’s death. The eel’s final metamorphosis—its transformation into silver, its journey into darkness, its vanishing—mirrors human mortality. Beyond science, this becomes emotional truth: what disappears still matters, what cannot be known still defines life. The eel becomes a witness to both endurance and surrender.

Lesson on Knowledge

True understanding may lie not in what the microscope shows but in the humility it teaches. Mystery, Svensson implies, is the world’s way of keeping us honest.

In its final metamorphosis, Svensson’s book turns elegiac. The eel—the creature that outlived ice ages and continents—is dying. Overfishing, dams, parasites, pollution, and climate change have fragmented its ancient journey to the Sargasso Sea. Populations in Europe have plummeted to less than 5 percent of their former levels. Svensson frames this crisis not only as ecological tragedy but as a spiritual one: in losing the eel, we lose access to mystery itself.

The Sixth Extinction

Calling upon Rachel Carson and Elizabeth Kolbert, Svensson places the eel’s disappearance within the context of the ongoing “sixth mass extinction.” It’s not just natural evolution—it’s human-induced. We have become the destructive current sweeping life away. For Svensson, this reflects humanity’s arrogance: we claim mastery over everything we study, even as our curiosity poisons the world it seeks to understand.

A Paradox of Protection

Efforts to “save” the eel—bans, breeding programs, electric tagging—reproduce the same impulse that created the problem. We try to control mystery rather than coexist with it. Svensson argues that maybe the only ethical approach is to let the eel be—“as close to zero interference as possible.” The paradox is sharp: to preserve mystery, you must stop dissecting it.

Symbol of the Enduring Unknown

As he closes, Svensson compares the eel’s potential disappearance to the loss of the dodo and Steller’s sea cow—creatures erased by human hunger. Yet, unlike them, the eel’s death would extinguish not just a species but a metaphor. The eel embodies everything unsolved, everything slippery about existence. To let it vanish is to let go of the reminder that the world is larger than our comprehension.

Final Reflection

The eel’s extinction warns you that when mystery disappears from the world, faith, imagination, and humility may vanish with it. In saving the eel, you save the part of yourself that still believes there’s more to know.