The following version of this book was used to create the guide: Roberts, Jason. Every Living Thing. Penguin Random House, 2024.

Jason Roberts's Every Living Thing tells the parallel stories of two men born in 1707 who would fundamentally shape how humanity understands the natural world: Carl Linnaeus of Sweden and Georges-Louis Leclerc, Comte de Buffon, of France. Through their contrasting lives, philosophies, and legacies, Roberts explores a central question: how do we organize and classify life itself?

Carl Linnaeus was born to modest circumstances in Stenbrohult, Sweden. His father, a reverend, initially planned for Carl to inherit his parish, but the boy's poor academic performance and obsessive interest in plants—earning him the nickname 'the little botanist'—led his disappointed parents to divert the parish to his younger brother and send Carl to medical school in Uppsala instead. There, cut off financially and starving, Linnaeus struggled until a chance meeting with Professor Olof Celsius in a garden won him crucial patronage. At Uppsala, Linnaeus developed his revolutionary sexual classification system for plants based on pollination methods, offering a streamlined alternative to rote memorization that made him wildly popular with students.

Meanwhile in France, Georges-Louis Leclerc inherited massive wealth from a childless relative, taking the noble name 'de Buffon' after the village he now owned. Where Linnaeus knew hunger and cold, Buffon enjoyed excellent schooling, European grand tours with the Duke of Kingston, and the leisure to pursue intellectual passions. His travels awakened genuine scientific aptitude, and he returned to plant exotic trees on his estate and develop probability theory (Buffon's Needle), earning early election to the prestigious Académie des Sciences.

Linnaeus's worldview was rooted in Biblical literalism. Believing all species were fixed, finite, and descended unchanged from Noah's Ark, he set out to create a universal taxonomy using Greek and Latin nomenclature. His system imposed order on nature through discrete categories, and after a difficult field expedition to Finland (which he detested), Linnaeus began developing his comprehensive classification system. Back in Sweden, initially struggling as a doctor treating venereal diseases, Linnaeus used his wife's dowry to fund a second edition of Systema Naturae. In this version, he classified humans into four racial categories—Europaeus albus, Americanus rubenscens, Asiaticus fuscus, and Africanus niger—encoding prejudice as scientific fact and establishing centuries of racist pseudo-science.

Eventually appointed professor at Uppsala University, Linnaeus attracted cult-like devotion, sending student 'apostles' on dangerous expeditions to gather specimens. Practically all would die on these journeys. Linnaeus published Species Plantarum, establishing strict rules: taxonomic names must derive from Greek or Latin, species must be named after invariant characteristics, and indigenous or folk names were banned.

Buffon, appointed to lead the Jardin du Roi in Paris, took a radically different approach. He hired the first female botanical illustrator and began writing Histoire Naturelle, which organized organisms around spectrums rather than discrete classes. The work became France's bestselling book. Where Linnaeus imposed Biblical certainty, Buffon embraced complexity and observation. Critically, Buffon observed that horse hooves contain the same bones as human feet, leading him to theorize that environmental pressure could drive species to change over time—essentially developing an early theory of evolution. His 'moule intérieur' (internal matrix) concept remarkably approximated modern genetics without knowledge of cells or DNA. Though required by Church authorities to include stylistic detractions of his evolutionary ideas, readers understood these as protective camouflage for revolutionary thinking.

Buffon rejected racial classifications, opposed slavery, and held progressive views. This stood in stark contrast to Linnaeus, who was deeply patriarchal—forbidding his talented daughter Elisabeth Christina from pursuing botany, enraging when she published a successful treatise, and forcing her into an abusive marriage she eventually fled. Meanwhile, his mediocre son Carl Jr. was positioned to inherit his professorship.

The 1758 tenth edition of Systema Naturae exposed contradictions in Linnaeus's system. By dramatically revising classifications to accommodate new research, Linnaeus validated Buffon's critique that his categories were arbitrary. He introduced fantastical human subspecies—Homo nocturnus, Homo caudatus, Homo ferus—most of which disappeared in subsequent editions, revealing a system built on insufficient evidence. Linnaeus died in 1778 after neurological decline, buried in Uppsala Cathedral. His son died shortly after visiting Buffon in 1782, and with no male heirs, the family coat of arms was destroyed.

Buffon died in 1788 at age 80, still working, his apparently happy marriage a contrast to Linnaeus's troubled family life. He dedicated his body to science and was dissected after death. Yet despite Buffon's theoretical superiority, Linnaeus's fame only grew. During the French Revolution, a pro-Linnaeus faction installed his bust in the Jardin du Roi (later renamed Jardin des Plantes), and four revolutionary calendar months bore Linnaean terms. The 1799 arrival of a platypus specimen—a creature whose bizarre characteristics invalidated neat categorization—proved Linnaean taxonomy's inadequacy, yet the system's dominance continued. In 1895, the International Commission on Zoological Nomenclature institutionalized Linnaean taxonomy as the governing framework.

Meanwhile, Buffon's protégé Lamarck developed transformisme (later translated as "evolution"), introducing terms like 'invertebrate' and 'biology.' Charles Darwin, drafting On the Origin of Species, was shocked when his editor Thomas Huxley pointed out similarities to Buffon's work and encouraged him to read the forgotten naturalist. Darwin discovered that Buffon 'had essentially anticipated all of his own theories. The identification of DNA's double-helix structure by Rosalind Franklin, James Watson, Francis Crick, and Maurice Wilkins, and the 1977 completion of the first genome mapping project, ultimately validated Buffon's moule intérieur concept.

Roberts concludes by noting that modern scientists still struggle with Linnaean taxonomy. Hundreds of species are believed to be accidentally classified multiple times, requiring commissions to remove redundancies. The 'boundary paradox'—where one species ends and another begins—exposes the arbitrary nature of discrete categories. Yet Linnaeus persists while Buffon remains largely forgotten. Every Living Thing argues that scientific legacy depends less on theoretical correctness than on institutional power, practical utility, and historical circumstance. The question of how we organize knowledge about life remains, as it was in the 18th century, profoundly unsettled.