We know why the candle was on Leonardo da Vinci’s desk—to bring light into the darkness. But why a ball and a small screen, perhaps made of thick paper, or of simple wood?
The “shadow drawings” suggest an answer.
When darkness fell and there was no other source of light in the room, Leonardo lit the candle and lined up the three—candle, ball, and screen. The small portion of the ball’s surface that directly faced the candle was brightly lit. But, moving outward in any direction, he could see that the remainder of the ball was left in varying degrees of shadow, as if the light never quite came its way. Where, then, did that light go instead?
Depicting the light not as we see it—as one solid beam—but rather as a set of discrete rays, he charted the individual destination of each and every one, line by line. Clearly, he knew something about the science of optics—or at least how light behaves when it hits an opaque object—because with exquisite precision he identified which rays would hit the ball in a straight line and be reflected straight back to the viewer (providing that brightness) and which, because of a more acute angle of incident (or impact), would hit it diagonally, leaving the edges of the ball in deeper and deeper shadow.
Again and again, he repeated the experiment, moving the ball closer to the light and then farther away, sometimes to the left and then to the right. He added a second source of light and examined the effect as the light from one source intersected with the light from the other. And he looked at the color of the ball and saw that it changed just as the shadows and light changed. And then there came the day he moved outside, ready to tackle the most difficult question of all—how the rays of the sun behave when they, too, meet an opaque object, such as a ball. Or, one must imagine, a human form.
For “nothing was more important to him than the rules of optics,” as one of his contemporaries noted. But in fact this obsession appears to have been very narrowly focused on just one aspect of optics: when and where light produces shadow. Every one of his notes beneath these sketches makes this point:
Every shadow made by an opaque body smaller than the source of light casts derivative shadows tinged by the color of their original shadow.
An opaque body will make two derivative shadows of equal darkness.
Just as the thing touched by a greater mass of luminous rays becomes brighter, so that will become darker which is struck by a greater mass of shadow rays.
Why this obsession with shadows? Because of some new invention or experiment he was considering? No. His goal was a different one: to learn how to paint.
As a young boy, when he was taken by his father to apprentice at the most important bottega (or workshop) of the early Renaissance, Leonardo had learned how to draw. Given a piece of charcoal or a quill pen dipped in ink, he could sketch a complex set of figures striking poses that were simultaneously true to life and emotionally evocative. Not surprisingly, while other new apprentices were sent to wash brushes or work on the mass-produced objects meant for the middle class, Leonardo quickly joined his master, Andrea del Verrocchio, at the easel, where the most important work of the bottega was done—the paintings meant for the Church or other important patrons.
But that same young man who could draw almost anything had yet to learn how to paint. And by “how to paint,” I am not referring to how to mix colors or apply them to the panel. I am referring to the sensibility of an artist who instinctively reaches for what makes a painting a great painting.
At the time, a quiet revolution was just starting to take hold in the world of Renaissance art, especially in the bottega of Verrocchio, one that would be based upon a new kind of revelation. This revolution was not the sort achieved through faith, which is what the Church wanted its paintings to convey. Nor would it be based upon the fixed truths rulers expected artists to use their talents to reinforce—that each of us must know our place in the larger scheme of things, deferring to the supposedly inherent nobility of those above us. Rather, this revolution in art was founded on the notion that a new and different kind of truth was waiting to be identified by our senses and made sense of by our minds—the truth that came from careful observation.
Just how this revolution would lead Leonardo to a new kind of art—one that would move viewers much more deeply, and one that speaks to us today in a way that most Renaissance painting does not—is the story this book tells. Crucial to that story, however, is the unraveling of a myth—a myth propagated, as my book will explain, by a renowned authority in the decades after his death: the notion of Leonardo as the iconic representative of two very different forms of genius.
Leonardo, it is commonly believed, is the artist who painted masterpieces such as the Ginevra de’ Benci, the Mona Lisa, and the Last Supper and drew the iconic Vitruvian Man and then underwent a metamorphosis of sorts. Somewhere in his late thirties and early forties, there is the emergence of a second Leonardo, the one who imagined inventions that would not come to exist until centuries later, from the parachute to the flying machine—the one who became fascinated by science and philosophy.
The artist and the scientist. Each exceptional in his own way, but representing different parts of the same man. The traditional characterization of this “dual Leonardo” is that the natural philosopher in him decided to work out scientifically what the artist had somehow vaguely intuited decades earlier.
Many of us who inadvertently helped perpetuate this dual-genius thesis had good reason to do so: scholars relied, after all, on documents Leonardo himself left us, in particular his “folios,” or notebooks. Many of the folios are dated, and based on those dates (with the exception of a few outliers, which were somehow ignored), it seemed that the vast majority of his shadow drawings, for instance, were done when Leonardo was well into his late thirties or early forties—in other words, long after he knew how to paint, and contemporaneous with his shift toward his philosophical investigation of nature. Science was called natural philosophy back then.
But do the dates written on the folios indicate what we have long assumed they indicate?
Let me explain.
It always surprises my students when I tell them that Leonardo was one of the least prolific painters of his time. Over a period of about four decades, he left us only between twelve and fifteen paintings (the number changes depending on the attribution of a handful of controversial works), and a number of these he never fully completed, including, it might surprise many to learn, the Mona Lisa. If he was not busy painting, then how did Leonardo spend most of his time?
He spent it writing.
Leonardo was an inveterate notetaker. He got into the habit of never going out without a little notebook, just in case something caught his eye. When it did, it could be how a flock of birds seemed to hang in midair, or how water moved through a canal, or something as simple as a cat playing in the street. He would take out his notebook and write about or sketch what he had seen, or he would make a note to himself to pursue a question he could not resolve on the spot.It always surprises my students when I tell them that Leonardo was one of the least prolific painters of his time.
A staggering 4,100 or so pages of sketches and notes, many supplemented with technical drawings in the style of the shadow drawings, have come down to us. But most scholars believe that what has survived represents no more than half of what Leonardo likely produced, which would mean he wrote around 8,000 pages. A more liberal estimate would place the number at 16,000. No other artist from the Renaissance left a written record of this size behind.
And here is the important point: there eventually came a time—when, exactly, we do not know, but certainly by 1490—when Leonardo believed that by organizing and expanding the notes and drawings he had made over the years, he could eventually produce a book, a book with the aim of teaching artists that “painting is philosophy.” He was aware that “few painters make a profession of writing since their life is too short for its cultivation” and that, in general, they “have not described and codified their art as science.” Determined to do something about this, he started to take notes on what we would now call “scrap paper,” and in Leonardo’s time, scrap paper would quickly succumb to the elements.
To preserve the most important of his writings and drawings, he copied each into a new folio and assembled these reorganized sheets of paper into sets of “folios” (which we now refer to as Leonardo’s “notebooks”). The shadow drawings he transferred to the largest folio set, suggesting that they were among his most important sketches.
These writings, both the reorganized folio sets and the scrap-paper writings that survived, could more accurately be described as a mass of rambling, fragmented, repetitious, and mostly undated notes that needed (and to this day need) thorough editing. For example, Leonardo thought nothing of writing about one topic one day on one sheet of paper and then continuing the discussion, months later, on another piece of paper. Or he would add notes on a new topic to a piece of paper that already contained notes on a different topic altogether. And everything he wrote, he wrote backward, so you need a mirror to read it. It is neither surprising nor unrealistic that some scholars threw up their hands when it came to these folios, describing Leonardo’s writings as nothing more than a “vast accumulation of words” and an unfortunate distraction from his paintings.
But other scholars, starting as far back as two centuries ago, began what can only be described as the painstaking detective work of putting these notes in chronological order. Over time, they learned to date even the flimsiest scrap of paper, sometimes by examining the spelling conventions Leonardo used—were they Florentine or Milanese? They studied the quality and size of the paper itself: Was it cheap or high quality? Large or small? Did it have a watermark? And did Leonardo prepare the paper with colors before writing or sketching on it? They also studied the tools he used—metal point or silverpoint? Chalk or pencil? Gall ink or just dark, diluted pigment?—and even the look of his handwriting: Was it firm or trembling? Above all, they looked to the layout of each of his folios for clues, paying particularly close attention to how he arranged drawings and words on the page.And here is the important point: there eventually came a time when Leonardo believed that by expanding the notes and drawings he had made over the years, he could eventually produce a book with the aim of teaching artists that “painting is philosophy.”
Two conclusions emerged from this detective work—conclusions that have shaped our understanding of the life and work of Leonardo. First, based largely on the only reliably dated folios, scholars concluded that Leonardo started to write in earnest only around 1490, when he was in his late thirties. (There are a few folios from earlier—between 1478 and 1480, when he was in his late twenties—but these were seen as exceptional.) Second, since everything he preserved in these folios was of a philosophical or scientific nature—even when they discussed painting, which a great deal of the material did—scholars concluded that these writings document Leonardo’s increasing distance from the world of art and his turn toward science and philosophy.
As this scholarly consensus formed, no one explicitly intended to dismiss the possibility that science played a role in shaping young Leonardo as an artist. It was just that Leonardo’s writings about the science of art from his mature years were so numerous in comparison to the surviving writings from his youth—and so few scholars considered the possibility that the stunning paintings produced by a young Leonardo might be the result of early exposure to science and philosophy. Nor did anyone challenge the notion that much of the material in the folios was likely a carefully copied version of discarded scrap-paper notes that could have been made years, if not decades, earlier. Rather, the details of young Leonardo’s possible engagement with science were neglected as attention was focused on his later writings and scientific pursuits.
This focus, however, has obscured as much as it has revealed. I am part of a group of art scholars who believe that the stress on answering the question of when and how Leonardo became a scientist has inadvertently prevented us from understanding something much more interesting: the possibility that Leonardo did not suddenly “become” a scientist at all. At the heart of the scientific mindset is curiosity—the need to understand and explain the seemingly inexplicable—and Leonardo showed a great deal of curiosity in his early work.
If science meant so much to the young Leonardo, why, you might ask, did he not, like Galileo Galilei, devote himself to science from the start? Why, of all things, painting? That question is easy to answer. It was the only outlet available to him. As an illegitimate son, he was denied the right to a higher education by the laws of the time. He was lucky to have learned how to read and write and to do elementary math. Had he not shown such a strong desire at an early age to observe and record nature in drawings, suggesting he might succeed as an artist’s apprentice, he would likely have been turned over by his father to the Church, to spend the rest of his days contemplating the divine.The details of young Leonardo’s possible engagement with science were neglected as attention was focused on his later writings and scientific pursuits.
Fortunately, while the law may have constrained the options available to illegitimate children, the arts themselves did not. To the contrary, an artist’s studio was the ideal setting for a child like Leonardo, who would be not only exposed to philosophical and scientific ideas but encouraged to seek them out—and to use them in the service of the arts. Of course, it is not just Leonardo who has come down to us as an example of “dual genius.” The Renaissance is still most often described as a time when art and science both thrived—but separately.
That is how I, too, saw the Renaissance until my undergraduate days at the University of Rome, when I attended a lecture by Professor Corrado Maltese. That day, he pointed out that we have lost sight of the true Renaissance. It was, he argued, a time when artists were deeply interested in science not apart from their art but because of it. Renaissance artists, the professor insisted, had enormous respect for what science could teach them, because Renaissance artists were taught that artists could make visible for society “what we know” only after science explained “how we know it,” an inversion of the artist-to-scientist hypothesis often applied to Leonardo. Artists and artisans followed science closely. From science, they learned how to be better painters, better sculptors, better metallurgists, better architects—better everything—and watched their art and that of others deepen as science explained more and more. Maltese taught us how to decode Renaissance art and to look for evidence of the scientific principles artists used to create their works.
Indeed, shortly after his arrival at the workshop of Andrea del Verrocchio, Leonardo would be given a fascinating opportunity. He would witness (and perhaps assist with) the painstaking experiments that his master conducted in order to design the golden orb that sits atop Brunelleschi’s dome of the Cathedral of Santa Maria del Fiore in Florence. He learned early on that there were philosophical and scientific truths that could help him make art, and that those truths could teach him what he desperately wanted to know—how to paint.
From The Shadow Drawing: How Science Taught Leonardo How to Paint by Francesca Fiorani. Used with the permission of Farrar, Straus & Giroux. Copyright © 2020 by Francesca Fiorani.