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Macmillan Childrens Publishing Group

The Shadow Drawing

How Science Taught Leonardo How to Paint

Francesca Fiorani

Farrar, Straus and Giroux



The Right Place at the Right Time

The teenage boy who showed up for an apprenticeship at the bottega of Andrea del Verrocchio was, it seemed, a work of art in his own right. He was possessed of such extraordinary beauty, it was said, that “nature seemed to have produced a miracle in him.” The boy’s name was Leonardo. He was at most thirteen or fourteen years old. His father, a well-connected notary, had sought out the apprenticeship for his son, for there was no finer or more dedicated teacher than Andrea del Verrocchio, and no artist who knew more about “the sciences, particularly geometry,” as an early biographer of Andrea noted.

The workshop of Leonardo’s new master was on the southeast side of Florence, about half a mile from the city’s magnificent cathedral, in the neighborhood of Sant’Ambrogio. It was there that painters, goldsmiths, sculptors, dyers, woodworkers, and stonemasons kept shop. The neighborhood buzzed with activity, and it remains as lively today as it was when Leonardo lived there five hundred years ago. Farmers from the countryside came every day to erect their stalls in the market, and visitors from other cities flocked there to buy the luxury goods for which Florentine craftsmen were famous. The small parish church lay at the heart of the neighborhood, and the craftsmen who lived nearby cared deeply for it even though it could hardly compare to Florence’s cathedral and its towering dome. It was in one of the small houses lining the neighborhood’s narrow streets, amidst the shouts of workers and shoppers, the clanging of tools from the workshops, and the scent of spices from the market, that Leonardo learned how to paint—and where he also sketched his first shadow drawings.

During the Renaissance, sons typically followed their fathers’ professions. The sons of doctors studied medicine at the university, those of craftsmen trained in their fathers’ workshops, and the offspring of merchants went to abacus school to learn essential skills of their trade. Had Leonardo been a legitimate son, he would have followed a similar path. He would have studied law at the university and become a notary like his father and his great-grandfather. But Ser Piero had conceived him out of wedlock with a household servant named Caterina. Leonardo’s grandfather proudly recorded the arrival of the boy, his first grandson, in the family memory book: “There was born to me a grandson, the son of Ser Piero my son, on the 15th day of April, a Saturday, at the 3rd hour of the night. He bears the name Lionardo [sic].” But in other, more fundamental ways, the boy was not part of the family. According to the laws of the time, illegitimate children were deprived of inheritance rights. They did not even have the right to attend university, let alone enroll in the guild of magistrates and notaries. Because of the circumstances of his birth, the boy was destined for a different career.

We know nothing about Leonardo’s childhood, but based on what we know about the upbringing of children in this period we can surmise that he spent at least a couple of years with his mother outside the village of Vinci, where she lived on a farm with the husband Ser Piero had arranged for her. After being weaned, which would have occurred anywhere between the ages of two and six, he would have moved in with his father’s family, taking up residence in either his grandfather’s house in Vinci or in his father’s house in Florence, where Ser Piero lived with his wife, whom he married after Leonardo’s birth. (Ser Piero would marry three more times and would father at least twelve legitimate children and numerous illegitimate offspring, meaning that Leonardo had many step-siblings.) In 1457, Leonardo’s grandfather, who was the head of the family, claimed the five-year-old Leonardo and Ser Piero as dependents on his tax return, a fact that has often been taken as an indication that the boy spent his childhood in Vinci. However, if we consider that Ser Piero, who lived in Florence, was listed as a dependent as well and that Leonardo developed close, lifelong relationships with the family of Ser Piero’s first wife, it seems possible, even likely, that the boy grew up in his father’s Florentine household.

At age six or seven, Leonardo began attending an independent grammar school, which was probably near his father’s house, to learn how to read and write in the Italian vernacular.

After a year or two, he began to attend an abacus school that offered lessons in Italian. Had he been a legitimate son, he would have gone to a Latin abacus school, which prepared students for higher education. For instance, Filippo Brunelleschi, the architect of the Florence cathedral’s famous dome and the son of another notary, had attended such a school a few decades earlier. But Leonardo was sent to an abacus school where teaching was conducted in the vernacular and the focus was on commercial mathematics: double-entry bookkeeping, the use of numerals of Indian and Middle Eastern origin, and algebra, all skills that merchants needed for their profession. At these schools, pupils read popular vernacular books such as The Flowers of Virtue, which argued for the rewards of virtue with tales about animals (Leonardo owned a copy of this book), and The Golden Legend, which contained fanciful stories about saints’ lives that made these holy figures seem fully human. Students might also read some of the modern classics in the vernacular, such as Dante’s Comedy, or some classical authors in handwritten translation, such as Ovid’s Letters or Pliny’s Natural History, a book Florentines read avidly as it recounted the stories of classical artists. Students also learned some basic Latin so that they could read contracts.

One wonders, though, how much authority Leonardo’s abacus teacher—whoever he was—held over the young man.

Leonardo was left-handed, and like many left-handed people he found it easier to write from right to left, instead of left to right. This way of writing allowed him to avoid smearing the fresh ink he had just applied to the page. He also wrote in reverse—that is to say, the words he set down were mirror images of the words one would expect to see, and could be read by others only if they were reflected in a mirror. The norm at the time was to force left-handed pupils to write with their right hand. Leonardo did learn how to write in normal script with his right hand, but throughout his life he disregarded his master’s teachings and followed his natural inclinations instead: he wrote with his left hand, from right to left, and in reverse.

When Leonardo was between the ages of twelve and fifteen, he was not sent to a monastery or directed toward a religious career, which was the path often chosen for illegitimate children. For instance, Leon Battista Alberti, who was also illegitimate, was sent to a seminary, learned Latin and the classics, and eventually became one of the most elegant writers of the Renaissance. Instead, Leonardo was assigned an occupation that many would have regarded as disgraceful for the son of a family of notaries.

He was sent to train in an artist’s studio.

* * *

Ser Piero had come to know the Florentine art scene well, as he routinely helped artists negotiate agreements with their patrons. In 1465, he had assisted Andrea del Verrocchio, an artist who stood out for his innovative work. Verrocchio loved music and good literature. He wrote verse, some of which is still preserved among his sketches. He was a superb draftsman and was also the first artist to smudge black chalk drawings with his fingers in order to create a smoky effect, a technique known as sfumato, which his most talented pupil would perfect in both drawing and painting. By the time Leonardo joined Verrocchio’s bottega and lived with his master, as was the custom for apprentices at the time, Verrocchio was a brilliant artist on a distinctly upward trajectory.

What was so special about Andrea? What did Leonardo learn in his bottega that he could not have learned elsewhere?

On the face of it, Andrea was a typical craftsman of the neighborhood of Sant’Ambrogio. He lived in the family home together with his sisters and their children, having never married. His workshop was nearby, possibly in the same building. He was deeply attached to his local parish, and included in his will a provision to be buried there (when he died in Venice, his body was transferred to Florence in accordance with his wishes). Near his house was the Osteria dei Pentolini, a favorite tavern of locals and foreigners alike that advertised itself with the resounding of empty pots hanging above the door (pentolini means “pots” in Italian). He mingled with fellow artists and kept his shop running with skill.

His bottega could easily have been mistaken for just another shop on a busy street filled with enterprises meeting the middle-class demand for luxury goods, portraits, and religious art. Most of these shops had a mostra, a short wall on the street to display the ready-made objects that were kept in stock for walk-in buyers. If Verrocchio’s bottega had one, it would have displayed candlesticks in marble or bronze, armor, bells, banners for festivities, small devotional images, and glass frames, as these were among the many items that were made in his workshop. He offered art objects in every price range and worked in expensive marble, in cheaper terra-cotta, in bronze, in wax, and in paint, which was the cheapest medium of all. He even made illustrated, handwritten books based on popular novellas and other stories.

But in Andrea’s bottega, any storefront activity would have belied the real excitement of what was going on deeper inside, where he taught the skills of the trade to a group of apprentices, many of whom went on to become some of the most important names in Renaissance art. In his workshop, he created custom works for specific patrons. These lucrative commissions came in every so often, mostly for paintings, less often for sculpture in bronze or marble. His customers included the Church, the powerful families of Florence, and the leaders of various towns and republics wanting to honor their heroes.

For the most part, Andrea trained his assistants just as any other Renaissance master trained his pupils. He took them in as boys, usually around the age of twelve. Although the modern view of Renaissance apprenticeships is that they were an opportunity to work closely with the best of the best, the reality was that most apprenticeships were one step up from servitude, for the system was little more than a means of obtaining inexpensive labor. The norm was for a master to contract with the apprentice’s family for a term of two or three years. The family paid the master a fee to train, feed, and lodge the apprentice.

No contract between Verrocchio and his assistants’ families has survived, but a contract that the Florentine painter Neri di Bicci drafted with an apprentice’s family in 1456 is typical of the time. The boy had to “come to the shop at all times and hours that I [the master] wish, day or night, and on holidays when necessary, to apply himself to working without any time off, and if he takes any time off, he is required to make it up.” We can presume Ser Piero signed a similar contract with Andrea and paid him a fee to train his son. We can also presume that Andrea trained his pupils in a similar fashion, even though most did not rise above the tedious labor of making copies of his works, filling in elements of landscapes or coloring buildings, and chiseling details.

Verrocchio’s apprentices did whatever menial work they were told to do. One day it could be helping out in the rooms where paintings were made, grinding pigments on porphyry slabs, mixing colors, or cleaning brushes. Large spatulas were used to lay base colors, medium brushes for figures and buildings, thin brushes for the finest details of faces and landscapes. Another day they might be called to work in the rooms dedicated to sculpture, a dirtier and nosier affair than painting; they became familiar with hammering tables, powdered gesso, wet terra-cotta, chisels, and hammers of various kinds—and, because Andrea was also a goldsmith and a bronze caster, they learned how to handle tools to solder sculptures, or feed small furnaces to bake terra-cotta and weld metals.

Andrea was what we would call today a “multimedia” artist. His range meant he had to pay dues to two confraternities, the Compagnia di San Luca for his work as a “painter and engraver [pittore e intagliatore],” and the guild of stonecutters and carpenters for his work as sculptor (scultore). But it also meant that Andrea could receive the highest praise to which a Renaissance artist could aspire. According to the poet Ugolino Verino, who knew many Florentine artists well, Andrea is “no less than Phidias” and “surpasses the Greeks” because “he both casts and paints.” In the Renaissance, artists from ancient Greece and Rome were considered superior to contemporary artists. There was simply no higher praise for a Renaissance artist than to be regarded as “no less than Phidias,” one of the greatest of ancient sculptors.

But for Andrea—and for the pupils who trained with him—to work as a multimedia artist was not only a way to win acclaim or to meet the demands of buyers of different means. In the words of Giorgio Vasari, the sixteenth-century artist and author who wrote the first biography of Verrocchio, it was a way “to avoid growing weary of working always at the same thing.” It was a way to keep one’s art fresh.

Indeed, if there was a dominant trait of Andrea’s artistic personality, it was his constant quest to make his works more expressive. He always looked for technical innovations that would allow him to achieve the best results. This was a lesson Leonardo would take to heart.

Andrea made something exceptional out of even the most common ready-made devotional images of the Virgin and Child, rendering the tender interactions between mother and son in exquisite detail. In some, the Child reached out for his mother’s face like any toddler would. In others, he tried to touch her nose, or played with her veil, or stood precariously on her lap. Often, Andrea allowed a small detail—a foot, a drapery fold, a hand—to escape the space of the painted image, intrude on the frame, and invade, so to speak, the real space occupied by the viewers of his works. This was an effective way to give viewers the illusion that they were so close to these sacred figures that they could touch their hands and garments. Soft light enhanced their simple gestures and revealed on their faces some of the most delicate and nuanced smiles and expressions that could be found in a Renaissance work. Florentine women of means felt close to these models of motherly love and flocked to Andrea’s bottega to buy them for their houses. These female figures with their indefinable soft smiles were among the distinctive features of his workshop, and became an important model for Leonardo.

Another hugely successful product of Andrea’s bottega was death masks. Though it may seem odd to us today, these were coveted artifacts, and Andrea’s were more coveted than others. One could find his death masks “in every house in Florence, over chimney-pieces, doors, windows and cornices,” according to Vasari. For the Medici family alone, Andrea made twenty of these “masks made after nature [maschere ritratte al naturale].”

The practice of creating death masks was ancient, dating back to the Egyptians, who used it to preserve the features of their pharaohs. It spread to ancient Rome, where it was used to keep alive the memory of family members, as Pliny wrote in his Natural History, and it became increasingly common in medieval and Renaissance Europe, first for kings, popes, and emperors, and later for famous poets and philosophers. The Florentine artist and writer Cennino Cennini left detailed instructions for making them in wax in his The Craftsman’s Handbook, the most popular art handbook of the period, and artists began using death masks as an aid in the making of portraits. The most famous portrait made after a death mask that any Florentine would have known was Brunelleschi’s; it was a prominent part of his tomb inside the cathedral whose magnificent dome he had built to universal acclaim.

The secret of Andrea’s death masks was a soft stone he had found in quarries near Siena and Volterra. It was ground into the finest powder, which, once it was mixed with water, proved even more malleable than wax; it adhered to the minutest crinkles of the human face so perfectly that the death masks that resulted looked “so natural that they appear alive,” as Andrea’s first biographer, Vasari, commented. And when it solidified, the mask was so lifelike that it could be reused as a model for portraits. A small tempera painting on paper representing Saint Jerome that is now in the Gallery of Palazzo Pitti in Florence was perhaps a portrait of a Florentine man made from one such mask: the wrinkles testify to the man’s austere life, just as they testify to the saint’s in the wilderness.

Early on, Leonardo came to learn the power of wrinkles to convey a sense of life’s experiences.

Andrea’s technical curiosity was not unusual in the Renaissance. The period is usually recalled for its rediscovery of ancient art and literature, but there was also a fascination with the revival of lost techniques of sculpting, building, and painting. Some artists rediscovered the use of linear perspective, a mathematically sophisticated way to represent space on a flat surface. Others rediscovered the Roman way of laying bricks for buildings. Still others rediscovered the ancient method of casting large bronze statues. Andrea, for his part, developed new techniques based on old ones to capture the delicacies of facial expressions, resulting in death masks that were even more realistic in their inwardness than those made by the ancients.

Leonardo learned from his master’s physiognomic investigations, but in due time he would turn those techniques inside out. Instead of using molds to capture the external appearance of faces, he looked at them from within. By way of dissections and drawings, he studied the bones, nerves, and muscles underneath the skin.

* * *

When Leonardo arrived at the workshop, Andrea was working on major commissions that had come his way thanks to the family that controlled the city. Florence was a republic, and the Signoria, the executive branch of the Florentine government, ruled the city from its palace. But the reality was that the Medici family had taken over the city—not just its politics and commerce, but also its cultural life, its art, and its symbols. Although they rarely held official positions, they stacked every elective office with their allies. The Medici palace—a square, three-story building constructed around a colonnaded courtyard—was the real seat of politics.

Unusually aware of the power of art to convey authority, the Medici filled their palace with ancient statues, medals, and coins, and commissioned cutting-edge modern works that masterfully supported their political agenda. For the most-public areas of the palace—the courtyard, the garden, the audience hall—they chose subjects with conspicuous political underpinnings. In the 1440s, they had commissioned the great Donatello, their favorite sculptor, to create a bronze statue of the most politically charged figure in Renaissance Florence: David, the king of Israel, who as a young boy slayed the giant Goliath with a sling in defense of his country. Donatello delivered a masterpiece, the first life-sized nude sculpture since ancient times. Now the Medici wanted another David, and they turned to Andrea, who had become their favorite sculptor after Donatello’s death.

A persistent rumor says that Andrea’s David is a portrait of the young Leonardo, but this is just a myth. What is true is that Leonardo was employed in Andrea’s workshop when his master created this statue, with its exceptional psychological charge.

It is hard to imagine that Andrea did not see this commission as his chance to assert his vision of art, contrasting it with Donatello’s. Unfortunately, Andrea—and Donatello before him—did not write about their art, and we can only speculate about what they wanted to achieve by looking closely at their works. At first glance, Andrea’s David looks a lot like Donatello’s. Both artists represented the biblical hero as a slender boy of about thirteen years of age with an anatomically accurate body. Donatello’s David is nude and has defined chest muscles. Andrea’s wears a leather tunic that reveals the boy’s bone structure and musculature underneath. Andrea rendered the body even more precisely than Donatello. An anatomically perfect leg emerges from a sturdy fold of the leather garment at the groin, while arm muscles and neck bones are expertly done.

What seems to set the two statues apart is how they handle David’s gaze. A gaze is not as conspicuous a feature as muscles and bones, but sculptors had learned how to turn their figures’ heads subtly to suggest the direction of their stare and, by extension, indicate something about their state of mind. Donatello’s David looks toward the head of Goliath at his feet, the contour of his sturdy metal helmet pointing down and reinforcing the downward direction of his intent look. He is immersed in his thoughts, introspective and closed off, pondering the consequences of his actions, his body fixed frontally.

In stark contrast, Andrea’s David stares straight ahead, his head turned to the side, his body slightly turned. He is eager to share with others news of his deed, engaging viewers with a subtle, triumphant smile that animates his beardless face. Verrocchio understood that a slight turn of the head meant also a slight torsion of limbs and muscles, and that those minimal changes in the positioning of the body make a big difference in how people perceive a work of art. His David addresses viewers directly and draws them into his mood and thoughts, but viewers need to move around the statue if they want to “see” all the gestures and torsions of the boy’s body.

Was this direct engagement with viewers something Andrea intended? Certainly, it was something Leonardo became obsessed with later on, when he wrote that painted figures “ought to move those who behold and admire them in the same way as the protagonist of the narrative is moved.”

It seems that Andrea understood instinctively that the future of art lay not with those who simply learned how to draw the face and body in ways that would generate a strong emotional response, which Donatello knew how to do. What Andrea seemed to be striving for was a kind of emotionally charged art that would draw viewers more deeply into the inner world of his subjects or, as we would say today, into their psychology.

But, of course, he was not alone.

From the early fifteenth century, artists and scholars aspired to an art that elicited strong emotional responses, just as that of the ancients had done. They read about ancient artists in Pliny’s Natural History and learned from Cicero what words could do to move people. But it was far from clear how to capture emotions and convey feelings with sculpture and painting. How do you identify and represent the emotional core of familiar narratives, stretch traditional techniques, and create figures of unprecedented expressive intensity? How do you reveal incredulity and belief, pride and conceit, vanity and contempt, fear and despair, with nothing more than pigments, metal, marble, or clay?

Verrocchio supplied an answer based on his close observation of nature. If the artist knew what to look for, he would begin to see that even the subtlest change of heart or mind involuntary triggered a change in the positioning of a person’s body and face; this change, in turn, created a new set of expressions, gestures, positions, even garment folds. These variations were made visible through the unexpected shadows they generated, darkening a garment previously shining in the light, or shading a part of the face that was lit earlier. Best of all was to spot the areas where light met shadow, where penumbras (“pen” meaning “almost” and “umbra” meaning “shadow”) occurred, where there was often some light but not enough for clarity, creating a fuzzy effect. It was such changes from light to dark—penumbras—that Verrocchio wanted his pupils to study and to depict in order to communicate the inner lives of their figures.

Drapery may seem to us a minor artistic subject, but Renaissance artists who were inspired by ancient artists regarded it as foundational for their art. Verrocchio seems to have been more aware than others that a fold that did not fall in the right direction or a crest that did not catch the light in the right way compromised how figures communicated their feelings to viewers.

It is no coincidence that Leonardo’s earliest works were studies of drapery. Later, Leonardo advised artists to make sure that “folds with dark shadows are not placed in the illuminated portions, and folds of excessive brightness are not to be made in the shaded portions.” The point was to make sure that folds do not “seem to be a pile of drapery cast off by man” or “completely cram a figure,” but rather to wrap people’s bodies so that the folds show “the posture and motion of such figures” and avoid “the confusion of many folds.” His suggestion to his peers was unequivocal: “as much as you can, imitate the Greeks and the Latins in the way in which the limbs are revealed when the wind presses the draperies over them.” Was he recounting in his own words his master’s teachings?

Indeed, garments were the real novelty in Verrocchio’s Christ and Saint Thomas, a sculptural group Andrea was commissioned to make in January 1467, when Leonardo was in his bottega.

The work was for an outdoor niche at Orsanmichele, the grain market located midway between the cathedral and the Signoria palace, next to some of the greatest Renaissance sculptures. There was Saint George, a marble work by the young Donatello that had stunned the city for its boldness about fifty years earlier. Then there was the Four Crowned Martyrs, a large sculpture of four men whom the artist Nanni di Banco had arranged in a circle inside a niche as if they were orators debating with one another. And then there was the magnificent Saint John the Evangelist, the first life-sized sculpture in bronze to be made in the Renaissance; it was the work of Lorenzo Ghiberti, the artist who had “rediscovered” the bronze technique of the ancients. No place was more visible—and more intimidating—than Orsanmichele for a sculptor who wanted to measure up to the great.

It took Andrea 3,981 pounds of bronze and more than fifteen years to complete his group sculpture, but considering what was at stake, it was not a lot of bronze, nor too long a period of time.

Young Leonardo was right there when his master transformed a traditional image into something completely original.

Instead of a lone statue of the saint, Verrocchio cast two statues, re-creating an encounter between Christ and Thomas that painters had represented often on flat panels but that sculptors had never rendered in the round. Although we do not know for sure, it is possible Andrea talked the patrons into accepting his conception, which required considerable technical inventiveness to stretch the amount of bronze that was allocated for one figure to fashion two, as well as a daring design in order to place two statues inside a niche that was meant for one. The result was “the most beautiful thing one could find and the finest head of the Savior that has ever been done,” as a Florentine chronicler put it. Christ and Thomas are hollow statues with no back; they are “an immense relief in bronze,” as Vincent Delieuvin, the chief curator of sixteenth-century Italian painting at the Musée du Louvre, aptly describes them. It was Andrea’s ingenuity that created the illusion of full, rounded figures whereas in reality there is only a hollow relief. Christ is fully inside the niche, but Thomas actually stands entirely outside it, with his right foot suspended in midair. He does not touch Christ’s wound. This was a departure from previous representations of the biblical story and from familiar accounts, including the very popular The Golden Legend, which reported that Thomas acknowledged Christ’s resurrections “not only by sight, like the others, but by seeing and by touching.” But the Bible made clear that seeing was enough: “because you have seen me, you have believed” were Christ’s words to Thomas (John 20:29). Andrea understood the spiritual significance of the encounter more deeply than popular writers: the point was that Thomas did not need to touch in order to believe, for sight was superior to touch.

Their garments capture the mood of the encounter. Ample wavy folds around Christ’s waist convey his serene calm, in contrast to the more jagged and fragmented folds of Thomas’s tunic that suggest his trembling. Andrea, it seems, was attracted not by the encounter per se but by Thomas’s emotional turmoil—by the rapid change in his state of mind from doubting and incredulity to revelation and belief. It seems these more difficult-to-communicate aspects of art were precisely what drove Verrocchio, and what later fascinated Leonardo.

Andrea was apparently dissatisfied with the traditional method of copying drapery. When cloth was casually thrown on wood or wax mannequins, the fabric shifted position easily, the folds changed shape, and light created new penumbras. He could not focus on and observe each fold in depth, but instead had to start anew whenever anything changed. But if he impregnated the fabric with a concoction of clay or wax and arranged it over a terra-cotta or wax relief of a figure in the position he wished to represent—sitting, kneeling, or standing—the folds would set permanently. He could also place a large candle or a torch in such a way that the light would hit the fabric and create deep shadows in the folds and dramatically illuminate the crests. When the fabric was dry and the flame was lit, he could copy the drapery from different points of view with great attention to the minutest variations of light and shadow. His pupils could gather around him and do the same. Years later, Leonardo wrote that “to draw in company is much better than to do so on one’s own” because an artist learns “from the drawings of those who do better than you” and because “a healthy envy will stimulate you to become one of those who are more praised than yourself.”

Verrocchio taught his pupils to carefully observe each fold and to capture the effect of shifting light. He did not want them to worry whether the drapery was going to be for the figure of an angel, a saint, a Madonna, or a pagan goddess. He did not even care if there were heads, hands, or feet attached to these drapery studies. All he cared about was that they captured the right light at the right angle. Because he insisted that the folds look real—because he wanted to capture not just the light and the movement but also the texture of the fabric—he experimented with different materials. In some instances he even drew on linen instead of paper.

This is not to say that hands and feet were unimportant to Andrea—to the contrary. Like the face, they could also convey emotion. Andrea had his pupils study hands in the act of praying, blessing, pointing, and greeting, but he did not have them work from real hands. He used casts because he wanted to “have them before him and imitate them with greater convenience.” One of those casts became the model for Christ’s large hand, with its many vessels and wrinkles, in Christ and Saint Thomas. It was placed at the very center of the niche, directing the viewer’s attention to Christ’s chest wound.

Andrea instructed his pupils to use a unique stock of casts, drapery studies, death masks, and drawings. He was an extraordinary draftsman. The pupils learned to combine them freely to create male and female figures for biblical or pagan narratives in any medium. For an angel in a painting of the Annunciation, they would select the drapery for a kneeling figure and combine it with a head in profile and a hand in the act of giving. For the Virgin, they would choose the drapery for a sitting figure and combine it with a frontal face and with hands in the act of praying or even in the act of welcoming, depending on which aspect of the religious narrative they wished to stress. But if another commission came in—be it a painting or a sculpture—that required a sitting prophet or king, they would know how to adapt that same drapery study they had used for Mary to a male figure, and they would also know how to combine it with different hands, feet, and heads.

This is why the figures that came out of Andrea’s bottega looked so expressive, intense, and emotionally charged. And this is also why the atmosphere of his bottega was so vibrant, so alive, that even established artists—among them Sandro Botticelli and Domenico Ghirlandaio, the future master of Michelangelo—often spent time there.

Andrea was a great master, and also a generous one. He shared his drawings and inventions even with his rivals. This is why figures striking identical poses or displaying the same drapery folds and even the same expressions appear in the works of so many different artists. As the poet Ugolino Verino put it around 1500, “Whatever painters have that is good, they drank from Verrocchio’s spring.”

In short, there was simply nowhere better for a teenage apprentice with talent and drive to be than the workshop of this Renaissance impresario. Leonardo saw his master at work, and would eventually become an impresario in his own right. Both master and pupil shared an affinity for technology and technical experimentation, and above all, they shared a deep interest in using art to communicate what people thought and felt.

* * *

Had young Leonardo not been so talented, he could easily have spent the rest of his days cleaning brushes, rising at best to the mind-numbing work of casting the religious figurines depicting the Mother and Child, or adding details to his master’s paintings. But the boy could draw—could he ever draw.

In the Renaissance, drawing was regarded as the foundational artistic skill. No artist could advance if he was not skilled at it. Apprentices started by copying their master’s drawings, then expanded their repertoire by copying other artists’ works, and eventually began to produce original works, sketching simple inanimate objects like jars and vases before progressing to buildings and landscapes. Human figures came last. Years later, Leonardo himself advised young artists to work slowly and “not to pass on to the second stage until you already have the first committed to memory and well practised.”

As an apprentice, Leonardo quickly learned to sharpen his already acute powers of observation. When he copied folds from a relief covered in wet cloth, the results were stunning; we can feel the effort young Leonardo put in, day in and day out, to capture the right light on a crest or the darkness in the recesses of a fold.

In some ways, though, Verrocchio was not the typical master. He did not train his apprentices as other masters did, in part due to his own surprising backstory. In 1452, Andrea killed a boy with a stone in the course of a fight outside the city walls. The death was an accident, and he was acquitted, but the incident set him back. He did not begin his own apprenticeship as a painter but rather as a metallurgist. He trained with a competent but minor goldsmith. We do not know exactly who his master was, but we know that Andrea was associated with masters who did not have what it took to make it in the ferociously competitive art market of Renaissance Florence. In 1457, just as Andrea, age seventeen, was expected to start to reap the rewards of his training and make a living with his art, one of the masters he was associated with went bankrupt. Andrea found himself out of work as a goldsmith. To make matters worse, around the same time, his father died, leaving him responsible for his stepmother, a younger brother, and two nieces.

In the middle of these hardships, Andrea retrained himself. He learned how to carve in marble, mold in terra-cotta, and cast in bronze. It is possible he learned sculpture from Donatello, who had returned to Florence from Padua in 1457. Or he might have trained with Vittorio Ghiberti, the son of Lorenzo Ghiberti and one of the finest bronze casters in Florence. He also learned how to paint, and his work displays a deep affinity with that of Filippo Lippi, a friar who left his order to marry a nun and to paint (his son, Filippino Lippi, would become one of Leonardo’s dearest friends). By the early 1460s, Andrea had opened his own shop and had turned his career around. He even started to take on apprentices, Leonardo among them.

There was one thing from his early training as a goldsmith that Andrea valued above all: the knowledge of how to produce the heat needed to melt and cast metal. He began to apply himself more and more to the sciences, and eventually turned his attention to light: how it disperses when it hits an object like the human face or body, how it refracts and reflects. The science of optics was becoming increasingly critical to his art, not just for what it could teach him about how to capture light, but also for how it could be harnessed as a tool. The importance of optics would be made dramatically evident in one of his most important commissions to date.

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In the late summer of 1468, Verrocchio was asked to create a golden ball, or palla, that could be mounted above Brunelleschi’s dome, atop Florence’s cathedral. The ball was so large and heavy that it would need to be welded in situ, high above the city. In order to make these welds, Verrocchio would need to create a set of “burning mirrors”—concave mirrors that reflected the light of the sun and concentrated it at a single point. Leonardo, who witnessed the making of the palla while an apprentice and who saw a burning mirror at work, called this instrument “a concave sphere that makes fire.”

Strangely, these burning mirrors are rarely mentioned in accounts of the cathedral’s dome. Equally curious is the fact that they are largely absent from accounts of Leonardo’s youth, though his own writings indicate the powerful influence they had on his thinking. If we are to connect Leonardo’s revolutionary art to the science of light and shadow, we must start with his dramatic introduction to the science of optics at the pinnacle of Brunelleschi’s dome.

Copyright © 2020 by Francesca Fiorani