Leonardo Da Vinci*

by Kathleen Krull

  Leonardo was out to question everything. Like others during the Renaissance, he was discovering he could think for himself: “Anyone who argues by referring to authority is not using his mind but rather his memory.” He was taking the first steps—baby steps—toward the methods of modern science.

  CHAPTER SEVEN

  Citizen of the World

  THE HEAVENS—or what we call outer space—were one of Leonardo’s obsessions in his notebooks, and his next job for Duke Sforza appealed to this interest.

  In 1490, the duke invited all of Italy’s elite to Milan for a great spectacle designed by Leonardo: the Feast of Paradise. The theme was to be astrology. Leonardo’s task was to create the party’s climax, a pageant called The Masque of the Planets. Perhaps it seems surprising to us that someone with such a critical mind accepted some of the ideas of astrology. But he did. Everyone did. However, Leonardo did scorn astrologers who made money by preying on foolish people. (He thought they should be castrated.) The visual possibilities of the astrological theme excited him to outdo himself. Hundreds of workers carried out his plans for the masque.

  At the stroke of midnight, after the dancing and feasting, the duke stopped the music. He raised the curtain on Leonardo’s latest creation: a gigantic revolving stage shaped like an enormous half-egg. Inside floated models of what were then considered the seven planets—Mercury, Venus, Mars, Jupiter, Saturn, the sun, and the moon. Earth was not considered a planet, and Uranus, Neptune, and Pluto hadn’t been discovered yet.

  Each planet revolved in its orbit, along with the signs of the zodiac illuminated by torches behind colored glass. Other torches flamed bright yellow, representing the stars. The effect was outrageous.

  At age thirty-eight, Leonardo had arrived. By now he had been promoted to what he considered the ideal job: ingeniarius ducalis, engineer-architect to Duke Sforza of Milan.

  Never had he enjoyed such financial stability. The duke gave him an entire wing of an old palace, opening onto the cathedral square, as a comfortable home and workshop. He also gave him precious land for a vineyard. Leonardo could finally think about building his own house. For now he supported a household of a dozen or so students, servants, and friends. His workshop was a hive of activity, buzzing with apprentices, with Leonardo as a gentle father figure.

  Best of all, he had plenty of spare time and the free run of the excellent library at the university. He had access to scholars and librarians. Some professors became his friends.

  He was far from wealthy, but now he did have money to buy books. He owned more than most scholars, including Ptolemy’s Cosmography. (It was Ptolemy who, in the second century, cemented the theory—still held in Leonardo’s lifetime—that Earth was the center of the universe.)

  Around this time, Leonardo informally adopted a ten-year-old boy he nicknamed Salai, or Demon. No one else liked the boy—he stole, lied, and constantly embarrassed Leonardo, who wrote, “He eats as much as two boys and causes as much trouble as four.” He might have started out as a servant—peasant children entered service at ten. But to Leonardo he also served as a model, a pupil and assistant, and a companion—almost a son, and someone to indulge. Whatever his faults, Salai stayed with him for almost thirty years.

  During his time in Milan, Leonardo was laboring on one of his most famous masterpieces, The Last Supper, painted on the wall of the dining room in a monastery. He would paint for days without eating or drinking. Or he might show up to study the mural for many hours, make one brush stroke, then take off. Two years passed. Eventually he finished, but alas, his experimental use of oil paints on the dry plaster wall was unsound. The mural began deteriorating during his own lifetime.

  Leonardo also devoted years of intense study to the duke’s favorite project, the twenty-four-foot-high bronze horse. Leonardo even dissected horses to study their anatomy. He became probably the world’s foremost expert on horses. And he was fascinated by the technological difficulty of creating a horse that big. But the bronze creature never got built.

  We know that by now he was wrapped up in scientific investigations.

  He became lifelong friends with Luca Pacioli, author of the first printed algebra book. A mathematician, Franciscan monk, and fellow disciple of Alberti, Pacioli was one of the most respected intellectuals in Italy and an important influence on Leonardo. Leonardo sought tutoring in math—never his best subject—from Pacioli. Math was changing at its most basic level. People were switching from the limited system of Roman numerals (no zero, no fractions) to the Arabic system, which we still use today.

  Pacioli also helped with Leonardo’s study of the Greeks—Archimedes, and also Euclid, whose ancient works in geometry were available in Italy. It was Euclid who had worked out the principles that the whole is equal to the sum of its parts, and that a straight line is the shortest distance between two points.

  Leonardo repaid Pacioli’s help many times over. He later illustrated the monk’s most celebrated work, Divina Proportione, which built on the five complex geometric shapes in nature as defined by Plato.

  Leonardo preferred to keep his scientific work secret. Pacioli was one of the few people Leonardo trusted enough to show his notebooks. Work on the meticulously illustrated notebooks was an ongoing nightly activity. Leonardo was beginning to organize them by themes—the first was to be optics, his theories about the eye and how we see.

  There was just so much to be learned, so much to discover. “Obstacles cannot crush me,” he proclaimed with resolve. “He who is fixed to a star does not change his mind.”

  He listed over 170 books he had read so far, from a textbook on surgery and a pamphlet about urine, to Pliny’s Natural History, Aristotle’s Physica, and various mathematical treatises. He was always on the lookout for new books: one on proportion, another on waterworks, a new translation of Aristotle on the heavens. He searched for years for a copy of Archimedes’ treatise On Floating Bodies. Archimedes remained the one ancient Greek he always respected; the others he came to disagree with.

  So starving was he for knowledge that, when he was past forty, he started teaching himself Latin, the scholarly language. This was so he could finally read the many books that hadn’t yet been translated into Italian. He never became expert, but the flexibility of his brain is impressive. Most people find it extremely difficult to learn a new language at that age.

  He followed any new development in geography or discovery of new plants and animals. He was mesmerized by maps. There is no evidence he ever journeyed farther than France—this was a time when most people never traveled farther than a day or two from their homes—but it was an electric era when people’s notion of the geographical world was expanding rapidly. This was thanks in part to Italian merchants who were pressuring traders and sailors for exotic temptations, like precious spices, from the Orient. After Christopher Columbus, financed by Spain, crossed the Atlantic Ocean and reached what turned out to be the “New World” in 1492, everyone’s horizons were broadening fast. Leonardo himself was friends with Amerigo Vespucci, the Italian navigator who explored the New World from 1497 to 1504. (Vespucci was also intelligent enough to realize the continent was not part of Asia as Columbus believed, but a new one—which was later named after him.)

  Practically the only facet of life that didn’t interest Leonardo was current politics. Around him swirled intrigue, executions, invasions, violent changes in regime—none of which he wrote about. He tried to remain above it all, considering himself a “citizen of the world.”

  Yet there was no way to stop politics from intruding on his life. The French invaded Milan. Sforza, Leonardo’s patron, was overthrown. In 1499, after eighteen years in Milan, Leonardo was forced to flee. He packed up his books, the precious notebooks, his collection of seeds (including lily and watermelon), and household items such as bowls and sheets—all in trunks to be carried by mules.

  Together with Salai and Luca Pacioli, the forty-seven-year-old artist-scientist began to roam.

  CHAPTER
EIGHT

  The Fabulous Notebooks

  AT THE TIME Leonardo’s mules were schlepping the notebooks around Italy, the pages were valuable only to their author. Today they are among the most precious things on the planet. The notebooks, the core obsession of Leonardo’s life, are what place him among the giants of science, not specific discoveries he made or new inventions he created.

  So what are they, exactly?

  We call them “notebooks,” but they are not bound like a typical notebook. Mostly they are loose sheets of paper casually gathered together and wrapped with different fabrics. Some pages are large. Others are only two or three inches square; these must be from the tiny blank notebooks he always kept tied to his belt.

  Leonardo went out of his way to make the notebooks difficult for any other person to read—tremendously out of his way. The main roadblock is his famous mirror-image script. His tiny writing goes backward, reading from right to left. The drawings aren’t backward, just the words.

  What was he thinking?

  Although he could draw with both hands, Leonardo remained left-handed. Was it simply easier or faster for him to write this way? Less smudging of the ink? Or was this eccentricity a function of his fear of scrutiny? Sometimes his work challenged church teachings. That could be dangerous. Was he worried that the notebooks could be used to incriminate him?

  We know he lived in fear of having his ideas stolen and published. Although there is no evidence that anyone ever tried to steal his work, he dreaded that someone else would take credit for his beautiful brain flashes.

  Sometimes he worried about “the evil nature of men”—that bad guys would misuse his inventions. For example, he invented a diving suit but worried that people would use it to stay underwater long enough to drill holes and sink the ships of their enemies. He didn’t trust many people.

  He could also have been merely following common practice. Many astrologers and alchemists of the day wrote in code. The famous French seer Nostradamus, whose life overlapped with Leonardo’s and who had run-ins with religious authorities, encoded all his predictions about the future.

  Historians argue over Leonardo’s reasons for being so baffling. In any case, much to a translator’s exhaustion, the notebooks must be held up to a mirror to be read.

  Even then, it’s a challenge. Like other writers of his day, he used inconsistent spellings and abbreviations, no punctuation, and capitalization only rarely. On days when he must have been feeling especially secretive, he wrote in code.

  And yet he was always addressing an imaginary readership—people who were brilliant, open to new ideas. Preferably geniuses. In the margins, he begged the reader to make sure his work got printed in book form—maybe, he hoped, after his death. So he wanted to be discovered and read. “I tell you . . . I teach you,” he wrote frequently.

  He boldly worked in ink—no revision. Lead pencils were uncommon in his day, anyway. When drawing the human body, he liked to work in red chalk, which he found good for conveying flesh. Getting paper was always a problem for him, and he obviously hated wasting it. He crammed every page with words and images. A page listing generous sums for Salai’s clothes would be filled up with a recipe for a powder to make plaster models, as well as several diagrams illustrating the play of light and shade. He mixed together shopping lists, thoughts for the day, tips for young artists, jokes whose humor hasn’t lasted, and passages from borrowed library books.

  The greatest hurdle for the reader is that his notes were not arranged in any logical order. He doesn’t seem to have been a linear thinker; he jumps from insight to insight, sometimes with no apparent connection. Sometimes he contradicts himself. But because so many pages are lost and because Leonardo never dated his pages, it’s impossible to know what his final thoughts on a subject were.

  And—surprise!—he left everything unfinished. He worked as if he had all the time in the world, even though he was already elderly for his era.

  The universally awe-inspiring aspect of the notebooks is the sublime quality of the illustrations. These were no amateur doodles. No one could draw as well as Leonardo. Some think that no one has since, until computer-assisted draftsmanship was invented.

  His text, although precise, witty, and often poet ic, was there to explain the elegant artwork, not the other way around. He was of the “one picture is worth a thousand words” school, and no one who has ever seen one of his notebook pictures could argue against that. To Leonardo the key to everything was saper vedere—“knowing how to see.” He wanted to be a sort of camera; he referred to “becoming like a mirror.” The way he illustrated anything was always clear, dramatic. He observed, then recorded.

  Whether he was studying the mysteries of flight; the relationship of the sun, moon, and stars; or the formation of fossils, he followed a pattern: recording ideas, doing experiments, and confirming or changing his ideas. It was a pattern revolutionary for its day—Leonardo was working his way toward the scientific method.

  CHAPTER NINE

  The Fabulous Notebooks, Part 2

  THE CRUMBLING PAGES of Leonardo’s otebooks are now five hundred years old. Ancient. How could they possibly be relevant to anything today?

  Prepare to be surprised.

  Leonardo was deeply interested in just about every area of science, but the three subjects he got the furthest on were anatomy, optics, and anything to do with water.

  Medicine then was dominated by the twenty-two volumes of the ancient Greek Galen—who lived in the second century—and his theories about complexion and humors. The body had its own normal balance of four fluids, or “humors,” as they were called: blood, phlegm, yellow bile, and black bile. Each of the four humors could be reduced to its basic qualities: hot, cold, wet, and dry. People’s “complexions,” or temperaments, could be classified the same way: sanguine (optimistic), phlegmatic (low in energy), choleric (easily angered), and melancholy (sad). So could organs—phlegm was associated with the brain, black bile with the spleen, and so forth.

  Disease was a result of a person’s “humors” getting out of balance for some reason. Diagnosis was a matter of doctors looking at the patient’s urine and deciding which humor was out of balance, with bloodletting and vomiting as the usual recommended remedies. The heavens affected the humors, so astrology played a vital part in diagnosis. Almost any symptom—and cure—could be connected to the alignment of the planets on that particular day. There was no need to know the actual structure of an organ or how it functioned.

  Leonardo, inspired by painting people from the outside, was determined to understand exactly what went on inside. There are plans in his notebooks for a whole book based on his drawings, to be called On the Human Body. Incredibly ambitious, it was to deal with how the body worked from the time it was a fetus right up until the moment of death. He wanted to explain the nervous system, the muscles and veins and capillaries, how the five senses worked, the flow of blood, each bone of the skeleton, every organ . . . everything. He wanted to see, in detail, how it all worked so he could understand how it all worked.

  He had been able to dissect some animals, but he was itching to do the real thing—human dissections. In anatomy classes at medical schools, cutting into a human body—even a dead one—was considered repugnant. Human dissections were rare and generally done on the bodies of recently executed criminals. It was more important to read Hippocrates (the “father of medicine,” born around 460 B.C.) and Galen (born in A.D. 129). Galen had dissected only dogs, pigs, and monkeys, yet his findings were applied to humans.

  Historians disagree about exactly when Leonardo began dissecting human corpses. It’s possible he may have started in the 1460s while still at Verrocchio’s workshop, to satisfy the master’s demand for accuracy in painting. A famous professor of medicine, Marcantonio della Torre, may have smuggled Leonardo into a hospital in Florence and gotten him going on cadavers. (Some historians think Leonardo actually lived at the hospital for a time.)

  After 1487, however,
he became much more systematic and skilled in his study of human anatomy. He worked alone, by candlelight and only at night, to avoid prying eyes. In total, he dissected some thirty dead bodies, most of recently executed criminals or homeless beggars.

  The more he learned, the more amazed he was at the intricacies of the human body: “I do not think that rough men, of bad habits and little intelligence, deserve such a fine instrument.”

  It is hard to exaggerate the creepiness of Leonardo’s anatomy studies. There was no refrigeration or formaldehyde, so a corpse would have started to decay immediately. For his own sanity, Leonardo had to work as quickly as possible. But to get the information for his notebooks—the structure of the heart, for example, drawn from several different angles, and with the layers peeled back like the skin of an onion—he had to be on intimate terms with a corpse for as long as a week. Presumably he tried to schedule dissections for the colder winter months.

  Here was an artist who didn’t like getting paint under his fingernails; how did he deal with being up to his elbows in guts and gore? He described it in his notebooks as disturbing, “living through the night hours in the company of quartered”—cut into pieces—“and flayed corpses fearful to behold.”

  A serene person in general, Leonardo was cool, calm, and collected about witnessing what most people today could not bear to watch. Besides dissecting, he observed prisoners being tortured (he sketched their facial expressions) and executed. He did a quick but extremely realistic drawing of a nobleman’s corpse dangling from a noose. People with amputated or deformed limbs—anyone who “broke the rules” of proportion—fascinated him.

  Saws and scalpels were his tools, some of them his own inventions. After separating the organs, he washed them thoroughly in water and a solution of calcium oxide, or caustic lime. Now, how to get them to keep their shape long enough for him to draw everything from three different angles? He came up with his own method: he injected the organs with wax.