a woman cleaning the Mona Lisa with a rainbow duster in mood lighting

Why Leonardo da Vinci’s brilliance endures, 500 years after his death

His creativity and foresight in science, engineering, and the arts continue to surprise and amaze today.

Leonardo’s “Mona Lisa” is believed to depict Lisa Gherardini, the wife of Francesco del Giocondo, a Florentine silk merchant. Every year, millions of visitors jostle for a view at the Louvre Museum in Paris. The painting, protected by a thick layer of glass that must be cleaned regularly, has never been restored.
This story appears in the May 2019 issue of National Geographic magazine.

In an instant, centuries collide—a moment unlike anything I have ever experienced. I have come to Windsor Castle to see the queen’s collection of Leonardo da Vinci drawings.

Outside the towering stone walls, tourists snap selfies and rummage through souvenir tea towels. Inside, past an arched gateway bedecked by gargoyles, Leonardo ushers me back to the Renaissance.

I can almost hear whispers of the artist as I gaze at a leather album bound in the late 1500s in the castle’s stately print room. Gold embellishments adorn the volume’s two-and-a-half-inch spine. The cover, stained and worn by the imperceptible fingerprints of generations past, reads: Disegni di Leonardo da Vinci Restaurati da Pompeo Leoni (drawings by Leonardo da Vinci conserved by Pompeo Leoni).

No one knows precisely how this album made its way to England, but its provenance is unambiguous: Leoni, an Italian sculptor, acquired Leonardo’s drawings from the son of the artist’s devoted pupil Francesco Melzi and mounted them into at least two volumes. By 1690, the Leoni binding, as it’s known, had landed in the Royal Collection, teeming with 234 folio sheets and the peregrinations of Leonardo’s inquisitive mind.

As Martin Clayton, head of prints and drawings for the Royal Collection Trust, lays out a selection of the pages—now separated into 60 boxes—the scope of Leonardo’s subject matter soars into view: botany, geology, hydraulics, architecture, military engineering, costume design, geometry, cartography, optics, anatomy. He sketched to make sense of unknowns, probing the enigmas of the universe with ink, chalk, and silverpoint.

The drawings are breathtaking in their lucidity. The most diminutive, a fragment smaller than a thumb, shows a female torso evoked in just a few muted strokes. The most iconic, rendered tenderly in red chalk and curved hatch marks, depicts a fetus curled up in the womb.

Everything is put to the test with visual precision: a study of drapery for the Madonna; mortars bombarding a fortress; the umbra and penumbra of shadow; a skull, a heart, a foot, and the sweep of the human face—from the radiance of Leda to the misshapen features of an elderly man.

“What you get most out of Leonardo’s drawings in some of his sheets is this completely unfettered way of leaping between subject matter,” Clayton says. “There’s something tremendously exciting about seeing a mind working in this incredibly broad way.”

An inherently curious note-taker and truth-seeker, Leonardo pursued knowledge voraciously. His to-do lists included jottings to “construct glasses to see the moon larger” and “describe the cause of laughter” as he sought answers to a cascade of questions: What’s the distance from the eyebrow to the junction of the lip and the chin? Why are stars visible by night and not by day? How do the branches of a tree compare with the thickness of its trunk? What separates water from air? Where is the soul? What are sneezing, yawning, hunger, thirst, and lust?

Although his paintings are far better known, Leonardo’s wealth of manuscripts and drawings lay bare the inner workings of his genius. His fertile mind—the range of hypotheses he tested, the intellectual, scientific, and philosophical journeys he launched—is evoked on every one of the 7,000 sheets preserved at Windsor, in libraries in Paris, London, Madrid, Turin, and Milan, and in the private collection of Bill Gates.

As the 500th anniversary of Leonardo’s death is commemorated this year, the artist’s notebooks are experiencing a renaissance of their own. Museums are mounting exhibitions of his sketches, and scholars are publishing new analyses, delving ever deeper into the full spectrum of his creations.

Most remarkably, pages from Leonardo’s notebooks are finding their way into the hands of experts in the very fields Leonardo studied, from medicine and mechanical engineering to music. Reaching back centuries, they’re reaping fresh insights, probing Leonardo’s work to inform their own. Even as science, medicine, and technology have pushed past the boundaries of what we can do and how we can do it, Leonardo’s notebooks reveal how much we still have to learn.

In the words of art historian and Leonardo scholar Martin Kemp: “Not one of his predecessors or contemporaries produced anything comparable in range, speculative brilliance, and visual intensity. And we know of nothing really comparable over succeeding centuries.”

Leonardo was born to unwed parents on April 15, 1452, near Vinci, a hill town in the rural Tuscan landscape between Florence and Pisa. Many believe his mother was Caterina di Meo Lippi, a local peasant. His father, Ser Piero da Vinci, held elevated status as a notary—a professional path that Leonardo would have been expected to follow had he not been born out of wedlock.

The town of Vinci proffered an inspiring backdrop for a boy with a capacious vision. From a terrace atop the village’s 12th-century castle, the Tuscan landscape reveals itself today as it would have in Leonardo’s youth: olive groves, dusky hills, and a mountain range off Italy’s west coast.

In Vinci, this vista is known as orizzonti geniali, or “genius horizons,” says Stefania Marvogli of the Museo Leonardiano—an allusion to Leonardo and the geography that saturated his childhood. A patchwork of divergent terrains coming together to form a coherent whole, it reflects the connections Leonardo sought in nature: patterns that unify the cosmos.

Little is known about Leonardo’s childhood. Records suggest that he lived with his grandparents in Vinci, where he received a rudimentary education. Sometime during Leonardo’s adolescence, his father likely recognized his artistic abilities and showed his drawings to a client, the artist Andrea del Verrocchio, who agreed to take Leonardo on as an apprentice in his Florence workshop.

From the beginning, Leonardo upstaged his peers and soon his mentor, with whom he collaborated on religious paintings and on the copper ball that sits atop Brunelleschi’s dome. Leonardo’s earliest known independent work, a pen-and-ink landscape of the Arno Valley, dates to 1473, when he was 21. Within several years, he’d received his first commissions: an altarpiece for a chapel in the Palazzo della Signoria and the painting “The Adoration of the Magi” for a group of Augustinian monks.

Leonardo left few personal reminiscences of his own, but we have glimmers of the man. He was almost certainly gay—his lifelong companions were male, and he was twice accused of sodomy, though charges were dropped in both cases. An animal lover, he bought caged birds at market and set them free. Left-handed and handsome, he wore rose-colored tunics and was admired for his singing voice, generosity of spirit, and social finesse. He would have been a very entertaining dinner guest, says Gary Radke, emeritus professor of art history at Syracuse University. “He wasn’t one of these inscrutable, pondering, grousing geniuses.”

Throughout his 46-year career, spent largely in Florence and Milan, Leonardo willed himself to knowledge, touched by an ever wandering eye and the determination to follow it. He studied Latin, collected poetry, and read Euclid and Archimedes. Where others embraced the perceptible, he scrutinized minutiae—geometric angles, the dilation of the pupil—bounding from one discipline to the next while seeking links between them. He sketched flowers and flying machines, designed war machines for his patron Duke Ludovico Sforza, crafted theatrical ornaments out of peacock feathers, and engineered a plan to divert the Arno between Florence and Pisa.

Leonardo documented everything in magnificent detail on the backs and corners of paper with tidy notes written in mirror script, from right to left. Some of these pages exist as loose sheets today; others have been bound into the volumes now known as notebooks or codices. There’s no clear order, even on a single page, and similar themes often appear on different sheets completed years apart. 
All of this makes it hard even for scholars to keep up with the brisk tempo of his mind, Paolo Galluzzi tells me as he thumbs through reproductions of Leonardo’s notebooks with a sense of wonder. Every time he made an observation, a question arose in his mind, which invariably led to another, says Galluzzi, director of Florence’s Museo Galileo. “He went sideways.”

It’s difficult to grasp Leonardo’s unparalleled ability to push past the work of his forebears. He did this by cross-examining his subjects and overturning his own verdicts. In the Codex Leicester, Leonardo investigates how water makes its way to mountaintops, ultimately rejecting his initial conviction that heat draws it upward. Instead, he realizes, water circulates through evaporation, clouds, and rain. “More important than discovering how mountain streams work was discovering how you would discover it,” says biographer Walter Isaacson. “He helps invent the scientific method.”

For Leonardo, the precepts of science—observation, hypothesis, and experiment—were critical to art. He moved fluidly between the two realms, grasping lessons from one to inform the other, says Francesca Fiorani, associate dean for the arts and humanities at the University of Virginia. His greatest gift was his ability to make knowledge visible, she says. “That’s where his power is.”

Nowhere is this more vivid than in Leonardo’s study of anatomy. He dissected human cadavers, teasing out underlying musculature in three dimensions to see for himself how a leg bends or an arm cradles. Leonardo’s contemporaries, including rival Michelangelo, studied muscles and bones to improve their artistic representation of the human body. “But Leonardo went beyond this,” says science historian Domenico Laurenza, based in Rome. “His approach to anatomy was that of a real anatomist.”

The scientific data Leonardo collected in his notebooks underlie every stroke of his paintbrush. His anatomical studies drilled down on the biology of facial expressions. Which nerve causes “frowning the brows” or “pouting with the lips, of smiling, of astonishment”? he queried in his notes. His analysis of light and shadow allowed him to illuminate contours with unmatched subtlety. He did away with traditional outlining, instead softening the edges of figures and objects in a technique known as sfumato. Optics and geometry led to a sophisticated sense of perspective, exemplified in “The Last Supper.” Acute observations allowed him to depict emotional depth in the people he painted, who appear sentient rather than stiff.

Leonardo’s inventiveness, however, came at a price. He irked his patrons with incessant delays, and many of his works went unfinished, including “The Adoration of the Magi.” Scholars have attributed this to his exuberance for new subjects and his perfectionism. It was also because the challenge of doing outweighed the expectation of getting it done. For Leonardo, it’s all about process, says Carmen Bambach, curator of drawings and prints at the Metropolitan Museum of Art in New York. “It’s not really about the endgame.”

Indeed the more knowledge Leonardo acquired through the studies in his notebooks, the more difficult it became to see a finish line in his art. “As he kept painting,” Bambach explains, “he understood that you could create such infinitesimal gradations of tone and transition from the highest, most intense highlight to the deepest shadow.” X-ray analyses of Leonardo’s work reveal copious revisions, known as pentimenti. Infinity became a very real concept that took on practical implications: There was always more to learn. “In many ways, intellectually, this is an unending process,” she says.

This may help explain why Leonardo never published his notebooks. He intended to complete treatises on many subjects, including geology and anatomy. Instead his sketches and manuscripts were left to his faithful companion Melzi to sort through. In the decades after Leonardo’s death, two-thirds to three-quarters of his original pages were likely pilfered or lost. It was not until the late 18th century that most of the surviving pages began to be published—more than 200 years after he died. As a result, Laurenza says, “we know very little about Leonardo’s legacy as a scientist.”

Leonardo’s inquiries, postulations, and discoveries were entrusted to those who followed. Centuries later we’re still catching up with him.

The legacy of Leonardo’s notebooks is palpable today. J. Calvin Coffey, foundation chair of surgery at the University of Limerick’s Graduate Entry Medical School in Ireland, was conducting research a number of years ago when he made an astounding discovery: An observation by Leonardo, circa 1508, confirmed a theory he was trying to validate. Coffey studies the mesentery, a fan-shaped structure that connects the small and large intestines to the back wall of the abdomen. Since the publication of Gray’s Anatomy in 1858 (then called Anatomy: Descriptive and Surgical), students have been taught that the mesentery is composed of several separate structures. But while performing an increasing number of colorectal surgeries, Coffey had begun to suspect that the mesentery was one continuous organ.

As he and his colleagues homed in on the structure’s anatomy to prove this hypothesis, Coffey found a drawing by Leonardo depicting the mesentery as an uninterrupted structure. Coffey remembers the moment distinctly. Initially, he glanced at it and turned away. Then he looked again.

“I was absolutely astonished at what I saw,” he says. “It correlated exactly with what we were seeing. It’s just an absolute masterpiece.”

In one overview of his team’s findings, published in 2015, Coffey included Leonardo’s drawing and credited him in the text: “We now know that da Vinci’s interpretation was correct.” Coffey shows a slide of Leonardo’s sketch in his scientific presentations, marveling at his ability to dissect the organ in its entirety, a feat complicated by the complex layering of the structure. “He was so honest in his interpretation of nature and biology,” Coffey says. “Even today, you will have surgeons who will not be able to replicate what he did.”

Leonardo’s visual acuity was driven by his abiding faith in nature’s design, whether a tree root or a hippopotamus. Human ingenuity, he wrote, “will never devise any inventions more beautiful, nor more simple, nor more to the purpose than Nature does; because in her inventions nothing is wanting, and nothing is superfluous.” Every artery, every tissue, every organ existed for a purpose—a revelation that changed the course of Francis Charles Wells’s career.

Wells, senior cardiac surgeon at Royal Papworth Hospital in Cambridge, England, happened upon an exhibition of Leonardo’s anatomical drawings at the Royal Academy of Arts in the Piccadilly neighborhood of London in 1977. The entry fee was one British pound; the payoff, immeasurable. “It just blew me away,” he says.

Wells was stunned by the scope of the artist’s investigations. After dissecting the body of a 100-year-old man, Leonardo presented the first description of atherosclerosis in medical history. “This coat on the vessels acts in man as it does in oranges,” he wrote, “in which as the peel thickens so the pulp diminishes the older they become.”

His research on heart valves, Wells’s specialty, was just as prescient. To understand how they work, Leonardo designed a glass model of the aortic valve filled with water and grass seeds, allowing him to conceptualize patterns of blood flow and how the valves open and close, details of which were finally confirmed in the 1960s.

More than anything, Leonardo’s sketches opened Wells’s eyes to the exquisite logic of the heart’s structure and mechanics—not just what the organ looks like but also why it evolved the way it has. One autumn morning Wells stands over a patient’s open chest in his Papworth operating theater and motions me closer.

“See it? It’s astonishing,” he says, pointing to the mitral valve. “Think of the complexity that the body has to go through to make this valve.” Wells’s surgical approach is guided by the maxim he learned from Leonardo: Each part of the valve’s complex makeup—its leaflets, cords, and papillary muscles—is meant to be there, designed to sustain the forces thrust upon it.

Leonardo filled his notebooks with inventions that were never built, including this apparatus designed to allow divers to breathe underwater. A pacifist, Leonardo stated that he wouldn’t divulge how to make his underwater devices “by reason of the evil nature of men.” He feared that such contraptions might be used to destroy ships and kill the people aboard.

Underwater breathing

Leonardo filled his notebooks with inventions that were never built, including this apparatus designed to allow divers to breathe underwater. A pacifist, Leonardo stated that he wouldn’t divulge how to make his underwater devices “by reason of the evil nature of men.” He feared that such contraptions might be used to destroy ships and kill the people aboard.

This has fundamentally shaped the way Wells fixes ailing valves. “You see that little thing in my forceps? That’s the ruptured cord,” he says. “That’s the source of the problem.” Wells could opt to remove the entire valve and replace it with an artificial model, an approach favored by many surgeons.

Instead I watch as he painstakingly replaces every cord with Gore-Tex sutures, preserving as much of the original structure as he can. Leonardo could not predict a surgical approach, but he taught Wells to look carefully, to stop and think, and to fully embrace the valve’s inherent and masterful ability to do its job, a capability Wells seeks to retain in every cardiac operation he performs. “That was the paradigm shift,” says Wells, who collected his insights in a 256-page book, The Heart of Leonardo.

A continent away, Leonardo’s Codex on the Flight of Birds has permeated the Stanford University Bio-Inspired Research and Design (BIRD) lab of David Lentink, a biologist and mechanical engineer. When I visit, Lentink hands me a piece of paper with queries explored by Leonardo that he and his 10 graduate students are still trying to answer: How does wing motion in air result in thrust? How do birds’ muscles control the flapping of their wings? How do birds glide? “All his questions are still relevant,” Lentink says.

Lentink and his team have access to high-tech tools that even Leonardo couldn’t have dreamed up. Sensors and high-speed photography allow them to measure the amount of lift that birds generate in flight. A nearly six-foot-long test section of a wind tunnel, which Lentink custom designed, simulates smooth air as well as turbulence, providing clues about how birds’ wings change shape during vastly different wind conditions.

One of the lab’s standout projects is a mechanical bird called PigeonBot, which has feathered wings crafted by Laura Matloff and a radio control system run by fellow grad student Eric Chang. Matloff used an x-ray microscope, capable of measuring one-millionth of a meter, to determine the characteristics of the feather surfaces and interactions between adjacent feathers. The skeleton and pin joints, which attach the feathers, were made on a 3D printer. PigeonBot is equipped with an accelerometer, a gyroscope, a barometer, an airspeed sensor, a GPS, compasses, and radio transceivers that transmit flight information to a laptop.

I meet the pair one cloudy morning in the hilly brush near Stanford for a test flight. As Chang says, “Ready!” Matloff thrusts the robot into the air; we watch it fly at about 10 meters a second until Chang brings it in for a landing. PigeonBot isn’t just for show. Reverse engineering a bird allows scientists to study flight mechanics in a step-by-step process and better understand the function of each body part—something Leonardo couldn’t do. Modern engineering may one day reward Leonardo’s ardent curiosity with answers to the mysteries he pursued. “I think we’ll get there,” says Lentink.

Just as Leonardo’s notebooks brim with bursts of clarity, they also include more tentative musings that flicker with possibility. Drawings contained in the Codex Atlanticus and several smaller notebooks prompted Polish pianist Sławomir Zubrzycki to investigate. He hungered to hear Leonardo’s music.

Among his many pursuits, Leonardo improvised melodies on the lira da braccio, a Renaissance-era stringed instrument, and studied the intricacies of acoustics and musical design in his notebooks. In 2009 Zubrzycki found himself transfixed by sketches for a viola organista, a keyboard instrument with bowed strings. Captivated by the possibility of one instrument fusing two musical families, Zubrzycki set out to build it.

None of Leonardo’s drawings offer a detailed blueprint. For four years Zubrzycki spent five hours a day researching and formulating his design. He tested wood samples, resolved that he needed 61 keys, and puzzled out how to build four circular bows covered in horsehair that could rub against strings to create music. As he brought the instrument to life, Zubrzycki drew on the same vital force that drove Leonardo: his imagination.

The result is spectacular. Painted in vivid blue with a red interior, Zubrzycki’s gracefully crafted viola organista combines the polyphonic capacity of a keyboard—allowing it to play multiple melodies at once—with the sensitivity and emotive range of strings. In music, as in everything else, Leonardo was never satisfied with the norm.

“He was interested in looking for the next possibility,” Zubrzycki says.

One summer evening, dressed in a formal waistcoat and polished black shoes, he sits down to play a concert of Renaissance music at Kalmar Castle on the southern coast of Sweden. Although his viola organista looks like a baby grand piano, it performs like a full-bodied string ensemble. Resounding and joyful, the rich complexity of its sound evokes the luminescence of Leonardo’s paintings—a musical sfumato with soft edges and lingering tones.

Leonardo ranked music as second only to painting, higher even than sculpture, describing it as “figurazione delle cose invisibili,” the shaping of the invisible. For the hundred-plus people in Zubrzycki’s audience, such an exalted moment occurred in a castle as the sun began to set over the Baltic Sea, when a few scribbles in Leonardo’s notebooks morphed into music.

Ute Goedecke and Per Mattsson, Swedish Renaissance musicians, were deeply impressed and moved by Zubrzycki’s performance. Leonardo “would have loved to see that somebody took his idea to the next stage,” says Goedecke, “and made something real out of it.”

Leonardo’s final foray, in the fall of 1516, took him to Amboise, France, where King Francis I, an enthusiastic admirer, offered him a stipend and the freedom to create whatever he wished. At 64, Leonardo moved into a modest château, now known as Clos Lucé, with his many drawings and the three paintings he never parted with—“Saint John the Baptist,” “The Virgin and Child With Saint Anne,” and the “Mona Lisa.”

From his bedroom window, Leonardo could see the king’s castle. Outside, the colors and light of the Loire Valley echoed the vistas of his childhood. During his years at Clos Lucé, Leonardo designed hydraulics for the kingdom, sketched plans for a new royal residence, and staged joyful celebrations for the king. Amid it all, he enjoyed simple pleasures: He ate soup.

Before he died on May 2, 1519, at the age of 67, Leonardo completed a series of deluge drawings, depicting cataclysmic billows of wind and water. Rampaging vortices, executed mostly in black chalk, they surge with urgency and tumult. In the end Leonardo turned his eye, as always, to nature.

Today Clos Lucé is a living monument to Leonardo, set in a sprawling park filled with sage and other plants Leonardo sketched. Children play on a parabolic swing bridge and a tortoiseshell-like armored tank, derived from Leonardo’s notebooks. Walking the grounds one sunlit day, François Saint Bris, Clos Lucé’s director, says he hopes the place where Leonardo spent his final years will inspire next generations.

It’s a goal many share. New research is providing fodder for future scholars. Laurenza and Kemp have collaborated on a fresh analysis of the Codex Leicester, which reveals that it may have influenced the birth of modern geology. And after more than two decades of meticulous research about Leonardo’s life and work, the Met’s Bambach is publishing a four-volume opus, Leonardo da Vinci Rediscovered.

Leonardo’s notebooks are starting to make their way to the greater public too. Galluzzi is spearheading an elegant searchable database of the Codex Atlanticus, the largest notebook. Isaacson imagines a day when all of them will be fully translated and digitized by a single international consortium. “Then we will see Leonardo in all of his glory,” he says.

Just as Leonardo saw no end to his pursuit of knowledge, his notebooks are poised for rediscovery and posterity.

“I keep thinking I’ve finished with Leonardo,” says Kemp, who has studied and written about him for five decades. “He keeps coming back.”

Claudia Kalb writes about the science and culture of genius. This is her third collaboration with photographers Paolo Woods and Gabriele Galimberti, who live in Florence. Their cover story on Picasso appeared in the May 2018 issue.

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