The following version of this book was used to create this guide: Labatut, Benjamín. When We Cease to Understand the World. Translated by Adrian Nathan West, New York Review Books, 2021.

Benjamín Labatut’s novel When We Cease to Understand the World is written primarily from the third-person perspective, although Labatut employs the first-person point of view in the final chapter, “The Night Gardener.” Labatut narrates each chapter in the past tense.

In the first chapter, the largely historical “Prussian Blue,” Labatut discusses the explosion of suicides, many of which involved cyanide, in Germany at the end of the Second World War. Labatut then explores the history of cyanide; he begins by detailing the discovery of Prussian Blue, a synthetic pigment that altered the 18th century European art scene. In 1782, a chemist discovered cyanide by mixing Prussian Blue with sulphuric acid. Labatut then recounts the first poison gas attack in history, which occurred near Ypres, Belgium during World War I. The attack killed every living thing on the battlefield. Fritz Haber, a Jewish chemist, oversaw the attack at Ypres. Haber became famous for the Haber-Bosch process, through which nitrogen could be drawn directly from the air. The process saved countless people from starvation. Haber, however, also employed cyanide in a pesticidal fumigant that was later used by the Nazis in their gas chambers. In a letter to his wife, Haber confesses his guilt that the Haber-Bosch process might allow excessive plant growth to drown out all other forms of life on the planet.

At the opening of “Schwarzschild’s Singularity,” Albert Einstein receives a letter from Karl Schwarzschild that contains the first exact solution to the equations of general relativity. In the midst of his calculations, Schwarzschild discovers the endless abyss (a black hole) that a star creates during its collapse. The discovery challenges the most fundamental aspects of general relativity. The possibility of this singularity tortures Schwarzschild during his service in the First World War. Labatut briefly describes Schwarzschild’s adolescence and successful early career. Schwarzschild grows seriously ill during the war and obsesses over a solution to his own incomprehensible singularity. He considers whether the dynamics of a collapsing star—extreme compression and concentration—could also apply to the human psyche.

In “The Heart of the Heart,” a Japanese mathematician named Shinichi Mochizuki publishes his Inter-Universal Theory, which claims to illuminate the complex foundations that underlie the conjecture a + b = c. Mochizuki refuses to defend his controversial claim, and he retreats into solitude. Labatut then describes the life of Alexander Grothendieck. Grothendieck, after a turbulent childhood, claims to have discovered the conceptual heart behind the entire field of mathematics. He achieves wild success, influence, and acclaim, yet he abandons mathematics after becoming involved in political activism. Grothendieck then moves to a remote village, begins to engage in radical fasting, and lives essentially as a hermit. In his final days in a hospital, a Japanese man (Mochizuki) visits him.

The novel’s titular chapter opens with Werner Heisenberg interrupting Erwin Schrödinger at a conference in Munich. Schrödinger believes he has found a simple, logical way to describe the inside of an atom. Heisenberg, however, advocates for a more radical, abstract, and incomprehensible solution.

A year before the conference, Heisenberg decamps to the German island of Heligoland. He goes on long walks and formulates a series of matrices meant to describe the inside of an atom. During one of his walks, he becomes trapped in dense fog. He works furiously and eventually becomes ill. As he hallucinates about the poets Goethe and Hafez, he solves his matrices. He brings the solutions to his mentor, Niels Bohr, who is extremely impressed.

Einstein, meanwhile, finds Heisenberg’s work both wondrous and disturbing, as it violates the central conceptions of classical physics. Labatut then describes the life of Louis de Broglie, a physicist who proposes that an atom is both a wave and a particle. Einstein believes de Broglie’s research will allow the tenets of classical physics to be applied to the subatomic world.

Labatut details Schrödinger’s unfulfilling, though relatively successful, early career. During a bout of tuberculosis, Schrödinger visits a sanatorium in the Alps. He attempts to formulate a wave equation built upon de Broglie’s proposals. In a fevered haze, he writes an equation. Slowly, Schrödinger becomes obsessed with the sanatorium director’s adolescent daughter, Miss Herwig. He begins to tutor her in math, and they discuss their shared interest in physics and religion. Eventually, he confesses his feelings to her. They both grow sick. Schrödinger visits Miss Herwig in her room and touches her as she sleeps; he then flees the sanatorium.

In Zurich, Schrödinger presents his wave equation to great acclaim. Heisenberg struggles to argue for the supremacy of his matrix mechanics. One night, Heisenberg visits a bar where a man forces him to drink a strange liquid. The man bemoans the role of scientists, like Heisenberg, in making the world incomprehensible. Heisenberg wanders through a park and experiences a hallucination involving lights, human figures made of ash, and a dead baby. He soon proposes that quantum objects can exist in multiple places and display multiple velocities. He shares his theory with his mentor, Bohr.

At a conference in Brussels focusing on quantum mechanics, Heisenberg and Bohr present their findings. Einstein continually challenges the physicists, yet he is unable to disprove their theory. In the years after, de Brolgie comes to accept Heisenberg and Bohr’s proposal. Schrödinger, like Einstein, continues to unsuccessfully dispute their work. Heisenberg’s uncertainty principle remains intact.

In the final chapter, “The Night Gardener,” the unnamed narrator stays at a vacation home in a small mountain town in Chile. He encounters a neighbor who gardens only at night. The neighbor believes that plants sleep at night, thus they are more amenable to movement. The narrator and his young daughter encounter several dead dogs in the forest. Someone in the town poisons dogs every year, apparently in order to control strays. The night gardener tells the narrator about Fritz Haber and his role in the creation of both chlorine gas and nitrogen fertilizers. The narrator describes the town, its small old-growth forest, and its lake. He bought his home from a former lieutenant, who left a neutralized grenade in the home. In the final pages, the narrator reveals that the night gardener is a former mathematician. The night gardener tells the narrator that lemon trees, before they die, produce an enormous overabundance of fruit. He remarks on the strangeness of this unconstrained growth.