The first thing I noticed—before the prose, before the argument, before the 7,200 surviving notebook pages—was the jacket copy. Isaacson’s previous subjects stare back from the author photo like a curriculum vitae: Benjamin Franklin, Albert Einstein, Steve Jobs. Each biography was organized around a proposition about genius that could be condensed into a TED Talk title. Franklin: the self-made polymath. Einstein: the rebel imagination. Jobs: the intersection of liberal arts and technology. And now Leonardo, who is apparently the ultimate intersection, the ur-innovator, the man whose to-do lists—“Describe the tongue of the woodpecker,” “Inflate the lungs of a pig”—are offered up to us like Silicon Valley affirmations suitable for framing.
Isaacson writes in his introduction that he “embarked on this book because Leonardo da Vinci is the ultimate example of the main theme of my previous biographies: how the ability to make connections across disciplines—arts and sciences, humanities and technology—is a key to innovation, imagination, and genius.” He is transparent about the project. The book is a monument of research, five hundred pages synthesized from decades of archival scholarship, and I want to be fair to it. The archival excavation is extraordinary. The reproductions are lavish. The narrative moves with the easy, confident muscularity of a writer who has done this before and knows exactly how to make a Renaissance genius accessible to a reader eating a sandwich on the subway.
And yet. The Leonardo who emerges from the archival evidence—if you read it clinically, if you attend to the fissures and silences rather than the hero’s arc—is a far more volatile, restless, and psychologically fissured figure than the one Isaacson wants to present. This is a man who scribbled “Tell me if anything was ever done” over and over again, in notebook after notebook, like a patient scratching the same wound. This is a man who penned apocalyptic visions of flood and annihilation, who dissected corpses by candlelight in conditions that would “deter you by your stomach,” and who could not finish a painting to save his professional life. To read that man’s notebooks and conclude that the lesson for us is to “Retain a childlike sense of wonder” is to perform a kind of violence on the material. Not quite a misreading. Something worse: a tidying.
The Trauma of the Illegitimate Observer
Leonardo was born in 1452 in the hill town of Vinci, seventeen miles west of Florence, the illegitimate son of Ser Piero da Vinci, an ambitious twenty-five-year-old notary, and Caterina Lippi, an orphaned sixteen-year-old peasant girl.
The identity of the mother was a mystery for centuries. Isaacson, drawing on research by the art historian Martin Kemp and the archival researcher Giuseppe Pallanti published in 2017, documents that Caterina was orphaned at fourteen, took care of an infant brother, lost her grandmother a year later, and was left to fend for herself at fifteen. She had a relationship with Piero da Vinci, who was prominent and prosperous and almost certainly already betrothed to his future wife, a shoemaker’s daughter named Albiera. Piero married Albiera within eight months of Leonardo’s birth, and shortly after arranged Caterina’s marriage to a local farmer named Accattabriga—“Troublemaker”—who, fortunately, does not seem to have been one.
Leonardo’s grandfather Antonio recorded the birth on the last page of a notebook that had belonged to his own grandfather: “1452: There was born to me a grandson, the son of Ser Piero my son, on the 15th day of April, a Saturday, at the third hour of the night. He bears the name Leonardo.” The mother was not mentioned. She was not mentioned in any birth or baptism record. She was, for the purposes of the family ledger, erased. And Ser Piero chose not to legitimize his son, a process that could have been accomplished by presenting a petition to a “count palatine.” Listed on a 1457 tax census by his grandfather as “non legittimo,” Leonardo grew up caught in a particular kind of socio-psychological limbo.
Isaacson notes that Renaissance Florence was, as the historian Jacob Burckhardt observed, “a golden age for bastards,” a time when popes and princes openly elevated their illegitimate offspring. But the important qualifier, which the book handles briefly, is that this applied to the aristocracy. For the upwardly mobile mercantile class—the notaries and guild professionals—illegitimacy created something subtler than shame: a structural exclusion. The historian Thomas Kuehn, quoted in the text, captures it precisely: the problem with bastards was that they were “part of the family, but not totally.” Because he was born out of wedlock, Leonardo was barred from the Arte dei Giuduci e Notai, the guild of judges and notaries to which his father, grandfather, and great-grandfather had belonged. Five generations of professional identity, severed. He was in the room but not of the family.
This is the crucible of the observer. The child who occupies that liminal position—present but illegitimate, loved but not quite claimed—learns to watch. He decodes unspoken rules, hidden resentments, the subtle recalibrations of power that happen around a dinner table. He develops an eye for surfaces because he has been denied access to the structure beneath.
The exclusion deepened through education. Barred from the Latin schools that prepared legitimate sons for professional life, Leonardo was sent to an abacus school for commercial math. He never mastered Latin, wrestling with grammar rules well into his thirties. He never learned rudimentary algebra. Throughout his life he referred to himself, with a volatility that oscillates between defensiveness and ferocity, as an “unlettered man” and a “disciple of experience”—discepolo della sperientia. “I am fully aware that my not being a man of letters may cause certain presumptuous people to think that they may with reason blame me, alleging that I am a man without learning,” he wrote in his notebooks. “Foolish folk!… They will say that because I have no book learning I cannot properly express what I desire to describe—but they do not know that my subjects require experience rather than the words of others.”
The grandiosity of this claim—that direct observation surpasses all inherited wisdom of antiquity—is a compensation so massive it constitutes a worldview. He would conquer reality not by reading about it but by looking at it harder, longer, and more obsessively than anyone before him. And this is where Isaacson’s framing and the clinical picture begin to diverge. Isaacson sees this as curiosity. I see it as a defense system.
In one of the most psychologically revealing passages in the notebooks, Leonardo recalled hiking among gloomy rocks and coming upon a dark cavern. “Having wandered some distance among gloomy rocks, I came to the mouth of a great cavern, in front of which I stood some time, astonished,” he wrote. “Bending back and forth, I tried to see whether I could discover anything inside, but the darkness within prevented that. Suddenly there arose in me two contrary emotions, fear and desire—fear of the threatening dark cave, desire to see whether there were any marvelous thing within.” Desire won. He entered. Inside he found the fossilized remains of a whale. But instead of wonder, the discovery triggered an existential spiral. He addressed the long-dead beast: “You lashed with swift, branching fins and forked tail, creating in the sea sudden tempests that buffeted and submerged ships… Oh time, swift despoiler of all things, how many kings, how many nations hast thou undone.” He then spiraled into a vision of apocalyptic deluge—rivers deprived of water, the earth burnt to cinders.
This is the psychological basement of Leonardo da Vinci. Curiosity was not a joyful thing. It was a compulsion to enter the dark cave, to confront the terrifying power of time and destruction, and to try to document it all before it swallowed him. Isaacson acknowledges this passage, but he treats it as a set piece. I keep returning to it.
The Theatre of the Mind and the Flight from Completion
In 1464 the twelve-year-old Leonardo moved to Florence and was apprenticed to the workshop of Andrea del Verrocchio. Florence was at its peak—a city of forty thousand people that had produced, in a single generation, Brunelleschi, Alberti, Ghiberti, Donatello, and a banking family powerful enough to be patrons to them all.
The essayist Benedetto Dei boasted in 1472 that “beautiful Florence has all seven of the fundamental things a city requires for perfection.” Verrocchio’s bottega was a bustling commercial factory producing everything from altarpieces to parade banners to the monumental two-ton copper ball that crowned Brunelleschi’s cathedral dome. It was less a refined atelier than a Renaissance startup.
The young Leonardo likely served as the model for Verrocchio’s bronze David—a strikingly pretty, effeminate boy of about fourteen with a tantalizing, slightly cocky smile and luxurious spiraling curls. This physical type—the epicene, androgynous youth—would become a defining obsession in Leonardo’s art. Kenneth Clark noted that this figure and its opposite, the craggy, nutcracker-jawed old warrior that recurs in the notebooks, are “the two hieroglyphs of Leonardo’s unconscious mind… Virile and effeminate, they symbolize the two sides of Leonardo’s nature.” I find this reading almost too neat, but the visual evidence is overwhelming. Page after page of the notebooks oscillate between these two poles as if they were magnets.
It was in Florence that Leonardo learned the art of pageantry. The Medici kept the populace docile through public spectacles, and the artists of the bottegas were conscripted to design the machinery of spectacle. Leonardo adored this work. He designed theatrical scenery, flying contraptions that relied on hooks and pulleys, and complex mechanisms—ingegni—that turned shallow stages into apparent depths.
He rendered the emotional reactions of over sixty characters in his underdrawings, eventually reducing the number to a still-overwhelming thirty. But as the art historian Francesca Fiorani notes, “He must have faltered at the thought of how to balance the reflections that bounce from one figure to another.” The optical problem became a psychological impossibility. All thirty characters had to reflect light and project shade that would influence, and be influenced by, the light and shadows of those around them. They also had to initiate and reflect emotions that would interact with the emotions of those around them. The computational load was staggering.
Because when Leonardo was tasked with permanent creations, something seized up. Consider the Adoration of the Magi, commissioned when he was twenty-nine by the monks of San Donato. He set out to paint a scene of spiraling emotion. He mapped the panel with mathematically rigorous perspective lines—a flawless geometric grid drawn with a ruler and a stylus. And upon this rigid scaffolding he superimposed a hallucinatory fantasy of twisting humans, rearing horses, and a resting camel.
He rendered the emotional reactions of over sixty characters in his underdrawings, eventually reducing the number to a still-overwhelming thirty. But as the art historian Francesca Fiorani notes, “He must have faltered at the thought of how to balance the reflections that bounce from one figure to another.” The optical problem became a psychological impossibility. All thirty characters had to reflect light and project shade that would influence, and be influenced by, the light and shadows of those around them. They also had to initiate and reflect emotions that would interact with the emotions of those around them. The computational load was staggering.
And so he abandoned it. Seven months after he was commissioned, his payments ended. He left the painting with the brother of Ginevra de’ Benci and departed Florence for Milan. The monks had to hire Filippino Lippi as a replacement. Lippi tried to follow Leonardo’s design, even including a commentator figure on the far right in the same pose Leonardo had used. But Lippi’s commentator is a calm, older sage—not the dreamy, distracted young man Leonardo had painted, whose body faces the infant Jesus but whose head is turned sharply away, looking into the distance, psychologically absent. That self-portrait—if that is what it is—is one of the most piercing things in the book.
This pattern of abandonment has attracted the inevitable retrospective diagnosis of ADHD. I want to be precise about why this bothers me. It is not that the comparison is impossible. It is that it is trivializing. To label Leonardo’s inability to finish the Adoration as a deficit of attention is to view the mind through the suffocating lens of modern productivity metrics. Leonardo’s failure was a surplus of perception. He saw too much. He saw the impossible complexity of the bouncing light, the infinite gradations of shadow, the relentless interconnectedness of the physical world. To finish the painting would require him to settle for an approximation of reality. For a man whose entire defensive architecture was built on observing the absolute truth of nature, approximation was tantamount to a lie.
What Isaacson gets right—and this is important—is that Leonardo’s failure to finish was not laziness. Martin Clayton, the curator at Windsor Castle, posited that Leonardo continued to refine Saint Jerome in the Wilderness over a span of thirty years, adding anatomical details he only learned from dissections in 1510 to a painting he started around 1480. Infrared analysis confirmed it. Leonardo clung to his works, carried them when he moved cities, and returned to them as he learned new things. He could not let go because there was always more to be learned. This is not procrastination in any ordinary sense. It is a philosophical position about the nature of knowledge.
The Mechanics of the Soul and the Anatomy of Terror
In 1482, Leonardo moved to Milan to serve at the court of Ludovico Sforza, “Il Moro.” He arrived not as a painter but wielding a ten-point job application letter that touted his abilities to design bridges, cannons, armored vehicles, and catapults. He promised machines “indestructible by fire and battle” and “cannons, convenient and easy to carry, that can fling small stones almost resembling a hailstorm.” Only in the eleventh paragraph, at the end, did he mention that he was also an artist. “Likewise in painting, I can do everything possible,” he wrote.
Almost none of it was true. His military engineering existed purely in his notebooks. He was a vegetarian who bought caged birds just to set them free, offering his services to a ruthless despot who spent 140,000 ducats refurbishing his palace and 16,000 on hunting hawks, while paying his court architects a pittance. The irony compounds when you learn, as Isaacson documents, that only one of Leonardo’s military inventions was ever actually built: the wheellock, a mechanism for sparking gunpowder in a musket, which was spread to Germany by a technician named Giulio Tedesco—“Jules the German”—who lived in Leonardo’s household. His famous scythed chariot, his giant crossbow with its eighty-foot armature, his turtle-like armored tank—all remained on paper. When the giant crossbow was finally built for a television special in 2002, the contemporary engineers could not get it to work.
How does a man who writes in his notebooks “Save me from strife and battle, a most beastly madness” reconcile his employment with butchers? Later in life he would briefly attach himself to the horrifyingly brutal Cesare Borgia, traveling with an army that massacred civilians at Senigallia. Oddly, tantalizingly, Cesare Borgia is not mentioned any other time in Leonardo’s notebooks. Isaacson suggests pragmatism. But there is a dissociative quality here—an ability to draw a scythed chariot with such beauty that the hatching strokes and billowing capes are worthy of a museum piece, while beneath those capes, bodies are being sliced in half. The aesthetic imagination and the moral imagination appear to operate on separate circuits.
Milan also brought Salai. Born Gian Giacomo Caprotti da Oreno, the ten-year-old peasant boy entered Leonardo’s household with a head of wild curls and was dubbed Salai—“Little Devil.” Salai was a thief, a liar, and a glutton. Leonardo’s notebooks are littered with accounting entries cataloguing his transgressions: “On the seventh day of September he stole a stylus worth 22 soldi from Marco… Giacomo stole it from me within a month and sold it to a cobbler for 20 soldi and with this money, by his own confession, he bought aniseed candy.” Next to one entry Leonardo scrawled: “Thief, liar, obstinate, greedy.” Yet he never cast him out. He clothed Salai in expensive pink tights and jeweled shoes for decades. The tolerance is revealing. Salai was the untamed, chaotic id that Leonardo, with his rigid perspective grids and fastidious to-do lists, spent his life trying to suppress. He kept the chaos close, in a controlled setting, like a researcher maintaining a dangerous pathogen in a sealed lab.
Two days after Salai arrived, Leonardo took him to dinner at the home of Giacomo Andrea da Ferrara, a dear friend described by Luca Pacioli as “as dear to Leonardo as a brother, a keen student of Vitruvius’s works.” Salai “supped for two and did mischief for four,” breaking three cruets and spilling the wine. This dinner, which Isaacson mentions only in passing, was one of those historical meals that makes you wish for a time machine. It happened just four weeks after Leonardo and the architect Francesco di Giorgio had traveled to Pavia to study a manuscript of Vitruvius in the Visconti library. The conversation that night—when not interrupted by Salai’s antics—was evidently about the ancient Roman’s description of a man spread-eagle inside a circle and a square. Both Giacomo Andrea and Francesco attempted their own drawings of the concept. Leonardo’s version, produced in this same period of collaborative ferment, would become the Vitruvian Man—the single most iconic image of the humanist project.
Ideas are generated in physical gathering places where people with diverse interests encounter one another. This is why Steve Jobs liked buildings to have a central atrium. At the court of Ludovico Sforza, Leonardo found his atrium.
Leonardo’s anatomical work began as an artistic endeavor—following Alberti’s injunction to understand the body from the inside out. But it morphed into an obsessive quest to locate the exact mechanical junction between the physical body and the human soul. He dissected cadavers in conditions that beggar modern imagination. In a grimly humorous to-do list, he warned potential anatomists of what lay ahead: “You will perhaps be deterred by your stomach; and if this does not deter you, you may be deterred by the fear of living through the night hours in the company of quartered and flayed corpses, fearful to behold.”
He performed an autopsy on a centenarian who had died peacefully in a Florence hospital. He peeled back the skin, sawed through the ribs, and systematically dismantled the old man’s vascular system. In doing so he produced the first clinical description of arteriosclerosis in medical history. “I made an autopsy in order to ascertain the cause of so peaceful a death, and found that it proceeded from weakness through the failure of blood and of the artery that feeds the heart… which I found to be very dry, shrunken and withered,” he recorded. He compared the thickened vessels to those of a two-year-old boy, noting that the network of veins “behaves in man as in oranges, in which the peel becomes tougher and the pulp diminishes the older they become.”
He documented every proportion, compiling structured data that merged the biological with the geometric:
Table 1: Anatomical Proportions as Formulated by Leonardo
| Anatomical Measurement | Proportional Rule Formulated by Leonardo |
| Top of nose to bottom of chin | Two-thirds of the face |
| Space between mouth and base of nose | One-seventh of the face |
| Mouth to bottom of chin | One-fourth of the face (equal to mouth width) |
| Chin to base of nose | One-third of the face (equal to nose length) |
| Width of the face | Equal to space between mouth and hair roots |
Why this accumulation of data? Isaacson suggests it was to understand “the universal measure of man.” That is the generous reading. The clinical reading is that it was a desperate attempt to exert control. If Leonardo could map every muscle, every proportion, every nerve ending, perhaps he could finally understand the moti dell’anima—the motions of the soul.
He was searching for the senso comune, the exact physical location in the brain where all the senses converge—the processing center where the soul resides and where emotions are translated into movement. He pithed a live frog, driving a needle into its spinal cord, and watched it die instantly. “The frog dies instantly when its spinal cord is perforated,” he wrote. “And previously it lived without head, without heart… Here therefore it appears lies the foundation of movement and life.” Leonardo’s experiment would not be described and illustrated again until the Scottish physician Alexander Stuart replicated it in 1739—two and a half centuries later. He was trying to surgically isolate the soul, to pin down the exact millimeter of gray matter where human anguish originates. I stare at Isaacson’s reproduction of Leonardo’s wax-injected brain ventricles and the cold precision of the enterprise is almost unbearable.
This obsession reached its zenith in The Last Supper. Commissioned for the dining hall of the Santa Maria delle Grazie, the mural is not a frozen snapshot.
It is a psychological detonation. Leonardo chose the exact instant after Jesus says “One of you will betray me.” The words drop like a stone into a still pond, and Leonardo paints the acoustic and emotional ripples radiating outward. Bartholomew leaps to his feet; Peter elbows forward, knife in hand; Judas recoils in shadow, clutching his silver; Thomas points a doubting finger toward the heavens. The novella writer Matteo Bandello, who watched Leonardo work from the refectory of the convent, described how he would sometimes stare at the wall for an hour, make one stroke, and leave. Leonardo told Duke Ludovico that creativity requires time: “Men of lofty genius sometimes accomplish the most when they work least, for their minds are occupied with their ideas and the perfection of their conceptions, to which they afterwards give form.” The perspective of the room is manipulated, accelerated, and artificially tilted to force the viewer’s eye into the psychological center. He was trying to paint the acoustics of betrayal. I am not sure anyone has done it better since.
The Geometry of the Ineffable: Optics, Sfumato, and the Elusive Smile
Leonardo’s friendship with the mathematician Luca Pacioli, who arrived at the Sforza court around 1496, gave his quest for certainty through geometry a new dimension. Pacioli, author of On Divine Proportion, taught Leonardo the subtleties of Euclid’s geometry. In return, Leonardo drew breathtaking, skeletal illustrations of complex polyhedrons—the rhombicuboctahedron, rendered as if suspended by string. Pacioli was also a magician, and he and Leonardo collaborated on a book of party tricks and mathematical puzzles called De Viribus Quantitatis—On the Powers of Numbers. The image of these two men—the friar-mathematician and the illegitimate artist-engineer—performing magic tricks for Sforza’s courtiers is one of the book’s quieter pleasures.
But Leonardo was continually frustrated by arithmetic. He was drawn instead to continuous quantities—the fluid morphing of shapes. He became obsessed with the lunes of Hippocrates and filled entire notebooks trying to square the circle. He filled the opening pages of one notebook with 169 attempts. It was not proven impossible until 1882, because π is a transcendental number, not the root of any polynomial with rational coefficients. Leonardo could not have known this. He kept trying.
If his anatomical dissections were an attempt to find the hard, physical borders of the soul, his studies of optics led him to a devastating contrary conclusion: there are no borders. In his scientific notebooks he recorded an observation that would fundamentally alter Western art: “The line forming the boundary of a surface is of invisible thickness. Therefore, O painter, do not surround your bodies with lines.” Through experiments with light, shadow, and the anatomy of the eye, he realized that a mathematical line is an artificial construct. It does not exist in nature. The edges of objects are blurred by the scattering of light, the intervention of atmosphere, and the physiology of the retina.
Drawing on the work of the eleventh-century Arab mathematician Alhazen, Leonardo placed a sewing needle directly in front of his pupil. The needle did not block his vision of the background; instead, it became a transparent fog. “If you place a sewing needle in front of the pupil as near to the eye as possible, you will see that the perception of any object placed behind this needle… will not be impeded.” Because the pupil is wider than the needle, light from behind the object still reaches the retina. This is a beautiful experiment—cheap, replicable, and instantly persuasive. I tried it myself while reading.
The discovery gave birth to sfumato—the technique of blending colors and edges so smoothly that they melt into one another like smoke. But sfumato is something larger than a painting technique. It is an epistemological concession. An admission that we can never perceive the absolute edge of anything. The world is inherently ambiguous. The man who wanted geometric certainty had discovered, through geometry, that certainty was an illusion.
Nowhere is this ambiguity more completely realized than in the Mona Lisa. Begun around 1503 as a portrait of Lisa del Giocondo, wife of a Florentine silk merchant, it became the repository for everything Leonardo knew about science, optics, anatomy, and psychology. He applied paint in microscopic layers of glazes—some just two to five micrometers thick—building up as many as thirty fine layers to create the shadows of her cheeks. The light penetrates these translucent glazes, hits the white lead primer coat, and bounces back, creating an illusion of luminosity that simulates living flesh. He carried the painting with him for the rest of his life. He never delivered it.
The smile is the clinical heart of the thing. Leonardo knew that the fovea, the central area of the retina, is attuned to sharp details, while the peripheral areas pick up shadows more readily. He painted the fine details at the corners of Lisa’s mouth so that they point slightly downward. But he enveloped the area around the mouth in deep, shadowy sfumato. When you stare directly at her mouth, your fovea catches the sharp downward details, and she does not appear to be smiling. Look away—at her eyes, at the background—and your peripheral vision picks up the shadowy curves, and the smile appears. It is an uncatchable smile. It flickers. It changes based on the mechanics of your own sight. “In this work of Leonardo, there was a smile so pleasing that it was more divine than human,” Vasari gushed. The clinical truth is darker. Leonardo used the mechanics of optics to demonstrate that we can never fully know the inner emotional state of another human being. The moti dell’anima are hidden behind a veil of flesh and light. We see only what our retinas construct for us. The ultimate observer had concluded that observation itself is flawed.
The Microcosm, the Macrocosm, and the Chaos of Water
If the human body provided Leonardo with the illusion of mechanical order, water provided him with the terrifying reality of chaos. Throughout his life, water was his greatest scientific and engineering obsession. He designed canals for Milan, dreamed of diverting the Arno River to starve the city of Pisa—a plan that Machiavelli supported and that ended in humiliating failure—and studied the mechanics of friction, deducing that the coefficient of friction for wood on wood is 0.25. He viewed water as the lifeblood of the macrocosm. “As the blood veins originate in that pool and spread all over the human body, so likewise the ocean sea fills the body of the earth with infinite springs of water,” he wrote. This analogy between the earth and the human body was the central pillar of his scientific humanism.
He filled the Codex Leicester—the notebook now owned by Bill Gates—with 730 separate conclusions about water flow. He made lists of sixty-seven different words to describe the movement of water: risaltazione, circolazione, revoluzione, sommergimento. He dropped millet seeds into glass tanks to watch the spiraling eddies. He recognized the principles of aerodynamics and fluid dynamics, preempting Bernoulli’s principle by noting that air travels faster over the curved top of a bird’s wing, creating lower pressure that keeps the bird aloft. The sheer density of observation is staggering. Isaacson handles it with care, but the effect in the original notebooks must have been overwhelming—page after page of water in every possible state, as if Leonardo were trying to exhaust the subject by sheer accumulation.
Table 2: The Microcosm / Macrocosm Analogy as Initially Theorized by Leonardo
| Human Body (Microcosm) | Earth (Macrocosm) |
| Bones supporting the flesh | Rocks supporting the soil |
| Lungs rising and falling with breath | Ocean tides rising and falling |
| Veins carrying blood | Underground rivers carrying water |
| Heart as the reservoir of blood | Ocean as the reservoir of water |
| Body heat pushing blood to the head | Earth’s heat pushing water up mountains |
But as he continued to observe and experiment, the analogy broke down. He realized that mountain springs are not pushed up from the ocean by the earth’s heat, because rivers flow just as abundantly in cold winter. Water circulates through evaporation and rain. The earth was not a giant human body. The macrocosm/microcosm analogy was flawed. And this is where Leonardo becomes most himself: when the beautiful theory dies at the hands of ugly facts. He did not flinch. He revised. Isaacson rightly holds this up as one of Leonardo’s most modern qualities—a willingness to abandon a cherished idea when observation demands it. A century before Galileo, Leonardo was practicing what we now call the scientific method.
He applied this same empiricism to the fossil record. Finding layers of fossilized shells and trace fossils in the mountains of Tuscany, he rejected the Biblical story of the Flood with an argument that is still beautiful in its simplicity: “If the Deluge had carried the shells three hundred and four hundred miles far from the sea, it would have carried them there mixed up with different species, amassed together.” Instead, the shells were found clustered in living colonies. The Earth had simply shifted over eons.
He became obsessed with the spiral—the geometric form of a vortex. He saw it in the curls of the androgynous youths he loved to draw, in the growth patterns of the Star of Bethlehem flower, and in the deadly whirlpools of a diverted river. “The curling motion of the surface of water resembles the behavior of hair,” he noted. In his notebooks we find curls of hair, eddies of water, and whirls of air sketched side by side, with stabs at the mathematics that might underlie all spirals. This was his deepest intuition—that the patterns of nature repeat across scales, that the same geometry governs a ringlet of hair and a hurricane. But spirals in water do not stay contained.
In the final years of his life, exiled in France and weakened by a stroke, Leonardo’s obsession with water culminated in the Deluge drawings. These are not scientific illustrations. They are apocalyptic nightmares rendered in black chalk and ink—massive, spiraling vortexes tearing apart mountains, uprooting ancient trees, obliterating humanity. In his accompanying notes, his usually detached voice descends into frenzy. He describes the dark and gloomy air, the terrified animals, the drowned sons, the mothers weeping over corpses. “Others, with desperate act, took their own lives, hopeless of being able to endure such suffering; and of these, some flung themselves from lofty rocks, others strangled themselves with their own hands.”
There is no mention of Noah. There is no salvation. There is no forgiving God. There is only the raw, chaotic, spiraling power of nature, destroying the fragile order that humanity has attempted to build. These drawings feel like the work of a man who has seen through the surface of things and found only the vortex underneath. When I look at them I do not think about Renaissance genius. I think about the cost of perception.
The Apocalyptic Deluge and the Futility of the “Key Takeaways”
In his conclusion, Isaacson attempts to distill the agonizing complexity of Leonardo’s life into a set of actionable lessons. They arrive in neat subheadings: “Be curious, relentlessly curious.” “Retain a childlike sense of wonder.” “Go down rabbit holes.” “Procrastinate.” “Make lists.” “Be open to mystery.” He even quotes Einstein—“I have no special talents, I am just passionately curious”—and invokes Steve Jobs, who “climaxed his product launches with an image of street signs showing the intersection of the liberal arts and technology.” Leonardo was Jobs’s hero. “He saw beauty in both art and engineering,” Jobs said, “and his ability to combine them was what made him a genius.”
I am not going to pretend that these lessons are entirely wrong. Some of them are even useful. But they constitute a particular kind of violence against their subject. They are the bullet points of the biographical-industrial complex—designed to make genius palatable and replicable for the aspiring entrepreneur reading on a flight to a conference. They take a man who was notoriously unreliable, plagued by insecurities about his illegitimacy and his lack of education, and who could not finish what he started, and they sand him down into a productivity parable.
Leonardo da Vinci was not highly effective. He spent his life wandering from patron to patron—from the Medicis to the Sforzas to the murderous Cesare Borgia to the King of France—trading spectacular fantasies for a comfortable stipend. To look at his to-do lists—“Describe the tongue of the woodpecker,” “Inflate the lungs of a pig”—and see only charming curiosity is to miss the profound anxiety of a mind that could not rest. He was compelled to measure the exact proportions of a face, to map the trajectory of a bouncing light ray, and to trace the nerves controlling a human smile because he was terrified of the void. He used geometry and observation as a shield against the abyss.
When he was approaching thirty, having failed to finish any major painting, his notebooks filled with expressions of anguish. “We do not lack devices for measuring these miserable days of ours, in which it should be our pleasure that they be not frittered away without leaving behind any memory of ourselves in the mind of men.” And the phrase he scribbled over and over, every time he tried a new pen nib: “Tell me if anything was ever done… Tell me… Tell me.” And the cry: “While I thought that I was learning how to live, I have been learning how to die.” Meanwhile, Botticelli was churning out finished masterpieces for the Medici. Botticelli was selected to fresco the Sistine Chapel. Leonardo was not.
When he lay on his deathbed in Amboise, his life’s work amounted to a handful of completed paintings, a few abandoned murals, and thousands of pages of unpublished, unorganized notes written in mirror-script. He had not published his anatomical findings. He had not published his treatises on water or flight. His companion Francesco Melzi, a young nobleman from Milan who had joined his household in 1507 and became a surrogate son and heir, was left to sort through the chaos. Melzi spent decades trying to compile Leonardo’s notes into a treatise on painting, but the full notebooks remained scattered and unread for centuries.
On what may be the very last page Leonardo wrote in his notebooks, he drew four right triangles with bases of differing lengths. He was still trying to understand the mathematical formula for keeping the area of a right triangle the same while varying the lengths of its legs—the endless pursuit of transformation. Then abruptly, he broke off. “I must leave off,” he noted, “because the soup is getting cold.”
Those are not the words of a man who has successfully executed the seven habits of highly creative people. Those are the words of a mortal man staring into the darkness of the cave, who has realized that despite a lifetime of relentless observation, the universe remains fundamentally unknowable, and time is running out, and there is soup.
If there are lessons in the life of Leonardo da Vinci, they are not sunny exhortations to “think different.” The real lesson is about the heavy, crushing burden of perception. To truly see the world as Leonardo saw it—to see the infinite interconnectedness of the rivers and the veins, the apocalyptic fury hidden in a drop of water, the fundamental ambiguity of a human smile—is not a recipe for productivity. It is a recipe for paralysis. And the tongue of the woodpecker? It can extend more than three times the length of its bill, retracting into the skull and wrapping around the brain to cushion it against the ten-times-fatal force of repeated impact. There was no reason Leonardo needed to know this. There was no reason I needed to know it either. But I looked it up, because he told me to, and now I cannot stop thinking about a small bird whose tongue protects its brain from the violence of its own persistence.
If you’d like to read the full book in EPUB or MOBI format, feel free to send me an email—I’d be happy to share a free copy with you. Please reach me at: thenovaleaf@gmail.com