Leonardo Da Vinci (7 page)

Leonardo grasped the principle that flooding water deposits layer upon layer of sediments (soil and sand), which turn into rock. At the same time, rivers erode rocks and carry their sediments to the sea, in a continuous cycle. He wrote, “The stratified stones of the mountains are all layers of clay, deposited one above the other by the various floods of the rivers.”

In Leonardo’s day, there were two theories about why fossils and shells were found in rocks on the tops of mountains. Some people believed the shells were carried there by the biblical Flood; others thought that these shells had grown in the rocks.

Leonardo pooh-poohed both hypotheses—such opinions “cannot exist in a brain of much reason.” From his direct observation of shells and fossilized seaweed during walks in the Italian Alps, he came up with a third theory, one that is closer to the modern one. Shell fossils were once living organisms that had been buried at a time before the mountains were formed: “Where there is now raised land, there was once ocean.” To Leonardo, as to modern paleon tologists, fossils indicated that the history of the earth extended far beyond human records (such as the Bible)—“things are much more ancient than letters.” Such theories would have offended a strict religious sensibility, as would his scrutiny of Bible passages for lack of scientific logic.

One day Leonardo wrote, “The sun does not move,” in large letters on a page all by itself. We don’t know exactly what he meant by this. He wasn’t sure—he contradicted himself elsewhere in the notebooks. But was he beginning to question Ptolemy’s ancient and still-popular view that the sun moved around the earth?

The notebooks covered a wealth of miscellaneous offerings—whatever interested Leonardo’s butterfly mind. He tried to come up with a formula for making a synthetic material, something like plastic. It combined saffron, poppy dust, and whole lilies boiled together with eggs and glue.

Numerous themes, however, recur over and over: for example, the manipulation of nature through technology. The pages detailed all sorts of machines he designed with gears, cogwheels, screws, and pulleys. He invented a bicycle that would have really worked. He borrowed freely from what others were doing at the time (as he did in all fields), but never without questioning the work or trying to improve it. Machines of all sorts fascinated him. In fact, Leonardo viewed the human body as a machine—the ultimate machine—capable of being understood by looking at its different parts.

Leonardo wanted to find new sources of energy. In an era when the main source of power was muscle (of men and horses), he looked at new ways of using water, wind, and steam. He constructed a device to measure the volume of steam coming off a certain quantity of boiling water. Some think he anticipated the invention of the steam engine hundreds of years later; at the very least, he understood the concept of steam as power. He also proposed using solar energy, trapped by mirrors he invented, to help out the textile industry.

And, of course, there was mastery of the air, his favorite and most obsessive dream. His notebooks played endlessly with this theme. He drew parachutes, gliders made from silk and reeds, wings with all combinations of strings and pulleys, and even a sort of helicopter with a whirling spiral of fabric above it. He puzzled about the best shape—should the flying object be a butterfly with four wings, a canoe with attachments, or more like a windmill’s sails? Whatever the shape, his flying devices anticipated sophisticated principles of aerodynamics, the branch of physics having to do with motion of the air.

His ideas were the results of years of observing birds and sketching them. “The bird is an instrument operating through mathematical laws,” he believed—laws that
could
be figured out and applied to human flight. “As much pressure is exerted by the object against the air as by the air against the body,” he wrote—a startling observation not fully developed until Isaac Newton in the seventeenth century. He observed bats and flies equally, and was a great admirer of the aerial techniques of bees. He borrowed ideas from everyone before him who had ever contemplated flying.

Historians agree that his contraptions were probably not technically workable, but they disagree as to whether he actually made or tested any flying machine himself. If he did, we have no record of it.

Leonardo wasn’t always right. For example, he was intrigued by the study of physiognomy, the “science” of evaluating a person’s character by his or her facial features. Like everyone in his time, he believed that a person’s inner value was reflected on the outside. That is, good-looking people were virtuous, and ugly ones were bad. (Physiognomy was all the rage until completely debunked well after Leonardo’s day.)

He believed in a sixth sense, “common sense,” that ruled the other five senses. It was located, Leonardo said, in the center of the brain, “between sensation and memory.” Like others of his day, he speculated (wrongly) about which sections of the brain related to distinct skills, and thought that nerves from the brain led directly to all body parts.

He was the first person to depict correctly the relationship of the small and large intestines, but in general he failed to grasp the digestive process. He was clueless about peristalsis (rhythmic contractions of the esophagus that propel food along), believing instead that food moved because of intestinal gas. He thought the purpose of the appendix was to relieve gas pressure. (Actually, it has no known purpose.)

His drawings of the reproductive system, based on Galen, were imaginative, but more inaccurate than accurate. His knowledge of women’s anatomy lagged behind his knowledge of men’s. Doctors at the time believed that a woman’s uterus had seven chambers; Leonardo accepted this at first, though he soon realized it was false. But he never challenged the ancient belief that during pregnancy, a woman’s menstrual blood travels up the blood vessels to the nipples to become the mother’s breast milk.

Sometimes his theories were more poetry than science: “Tears come from the heart and not from the brain,” he once wrote. He believed that children who were born out of love and desire would become intelligent and beautiful, while “unworthy” children would result from relationships of reluctance or scorn.

Partly because he was so far ahead of his time, his descriptions of experiments and theories were sometimes confusing. The proper scientific vocabulary simply didn’t exist yet.

His desire to link things could lead him astray; he tried to make connections or parallels that didn’t exist. Leonardo believed that, just as the heart inside our body pumps blood, an “underground” heart was the source of rivers, instead of the water cycle we know today.

He was always stretching to formulate all-encompassing principles—“everything travels in waves,” “every natural phenomenon is produced by the shortest possible route,” “motion is the principle of all life.” Sometimes thinking big like this caused Leonardo to see patterns not always there. In his most famous drawing, the anatomically correct Vitruvian Man, he showed how the human body could be both a square and a circle. These shapes, he theorized, formed the basis of everything in the world. In this case, his theory was incorrect—another example of his seeing too much interconnection.

Sadly, he never gained mastery over mathematics, especially algebra. He even occasionally made basic mistakes in his arithmetic. He’d add up a list of numbers in his notebooks—and come up with the wrong total.

But in whatever he was investigating, Leonardo accepted nothing at face value. His theories were based on observation, documentation, and proof: “There is nothing more deceptive than to rely on your own opinion, without any other proof.”

In the thousands upon thousands of pages in the notebooks, he was thinking like a scientist.

CHAPTER TEN

“I Have Wasted My Hours”

FROM 1500, WHEN Leonardo turned orty-eight, until just before his death in 1519, he was essentially homeless. Without even a country to ground him, he lived at times from day to day. A steady, sympathetic patron was once again proving elusive.

Traveling about with his small household made up of Salai and Luca Pacioli, he tried, within his limited means, to act the part of a refined aristocrat. He had the best horses. His servants were always well dressed, and he himself wore brocade and other fine fabrics.

In his trunks were precious cargo, forty books and his secret notebooks, except when he thought he might be in personal danger. Then he would leave them in a monastery, with someone he knew, for safe-keeping.

At least one observer noticed that he had grown “weary of the paintbrush.” He often turned commissions over to his assistants. The reason to accept art commissions was to finance his experiments. He spent his days observing, measuring, dissecting, questioning, weighing, and analyzing—and cataloging it all in his notebooks.

In Florence, after the overthrow of the pleasure-loving, free-thinking Medici in 1494, the most powerful person was a teacher of religion named Girolamo Savonarola. In 1496, he staged a mass burning of what he considered immoral books and works of art. Luckily, only a few trusted friends knew about Leonardo’s notebooks, or even of his interest in science. But many of his friends, labeled decadent, suffered under Savonarola.

For a while Leonardo designed weapons and fortresses for the most notorious of Italian war-lords, Cesare Borgia, duke of Romagna. Duke Borgia was out to conquer all the city-states of Italy, murdering anyone who stood in his way. Many historians have noted the irony here: Leonardo, who despised war and called it “
bestialissima pazzia”—
beastly madness—working for such brutal bosses. But this was the highest-status work available to him. He couldn’t afford to turn it down, and he was genuinely interested in devising anything mechanical. In this case, the job gave him the liberty to explore libraries and meet intellectuals all over Italy. He became friends with Niccolò Machiavelli, the important Italian political writer and statesman.

Wherever he traveled, he drew gorgeous maps, depicting geography with more detail and accuracy than any previous cartographers. But after nine months, Borgia’s atrocities may have proved too upsetting to Leonardo, who quit his post.

In 1504, he was invited to depict a Florentine battle victory for the city’s town hall. His archrival, the twenty-nine-year-old Michelangelo, was invited to paint another battle scene at the same time on another wall in the same room.

The two geniuses had never gotten along. Michelangelo showed no interest in science, which to Leonardo meant his art was inferior. Michelangelo had once publicly insulted the older artist for his habit of leaving things unfinished. Leonardo, for possibly the first time in his life, had no instant come-back. He just blushed.

Leonardo put three years into his battle scene. He struggled to convey all the horrors of war. But while he was experimenting, trying to achieve the most brilliant colors possible, the paint on the wall ran and . . . well, he never actually finished the painting.

Leonardo also worked on several portraits during these years. The only one that survives is one he never titled. We call it the
Mona Lisa
. Leonardo seems to have had a special affection for the picture, for he never sold it, taking it with him on all of his subsequent travels.

Leonardo’s worries would have been eased had he been able to count on a family inheritance. But when his father, Piero, died in 1504, Leonardo’s meddling half brothers and sisters arranged to deprive their illegitimate sibling of any part of the estate. Then, a few years later, his favorite uncle, Francesco, died, specifically leaving everything to Leonardo. His siblings fought him on this as well. After a year in the courts, Leonardo prevailed and wound up with a small piece of land and money.

For a while he worked for King Louis XII of France, who was then living in Milan. Leonardo’s job was building mechanical toys and other entertainments. Until he was an old man, Leonardo kept his love of toys, pranks, and riddles. Part of him remained childlike, playful, and open.

When asked to design a garden, Leonardo came up with a Renaissance Disneyland. It had musical instruments powered by water, a copper aviary for birds overhead, and miniature lakes with waterfalls to keep wine chilled. It even had playful sprays of water, “if one wanted to sprinkle the ladies’ dresses for fun.”

He and his intellectual friends gathered for dinners where they talked about science—and also fashioned paintings and sculptures entirely out of food. He met seventeen-year-old Francesco Melzi, the well-educated son of an aristocrat. Melzi was interested in everything Leonardo was doing and wanted a career as an artist. He joined Leonardo as a pupil and stayed with him for the rest of his life. At times, Leonardo lived on the Melzi family estate near Milan, sketching the dramatic countryside and designing improvements to his hosts’ deluxe villa.

All this time, of course, Leonardo was continuing to fill the notebooks. And he felt ever more pressure to put his work in some kind of order before he died. He was racing against time to arrange the information in one grand encyclopedia that people could read and learn from.

But the more he looked at the results of his years of investigation, the more dismayed he was at the chaos. The labor needed to sort out the bundles of unrelated papers was overwhelming.

So he put it off.

Organizing was a type of busywork that didn’t really fit his personality. He reveled in flashes of insight. The actual cataloging of his insights would have cramped his style. And it wasn’t as if the disorganization prevented him from carrying on. He had an extremely high tolerance for confusion—said to be a trait that many geniuses share.

Also, by 1515, no books could be printed in many regions without church permission, and he may have dreaded the process of censoring his notebooks in order to satisfy others.

Perhaps he lacked confidence in his ability to write proper scholarly books. He definitely wasn’t up to writing effectively in Latin. He must have been nervous about his writing in general, because he sometimes asked friends to write important letters for him. At times in the notebooks, he worried about being laughed at. Perhaps he was plagued with depression, with bouts of sadness that sapped his energy. In any case, the notebooks remained notebooks. “I have wasted my hours,” he mourned.