by Shana Priwer
47
Observe and understand
Leonardo's scientific pursuits have earned him a firm place as the first of the true modern scientists. In fact, if he hadn't also been such a talented artist, he might be remembered as a scientist who “sketched a little” on the side. Leonardo was uniquely placed historically, bridging the gap between the hocus-pocus of the Medieval period, and inquiries of “modern” science. At the end of the Dark Ages in the fifteenth century, the scientific discoveries of classical Rome and Greece had been largely abandoned in favor of biblical teachings, which were taken as literal truth by most of the population.
Leonardo broke with this tradition by actually asking questions, and from his earliest days, he made detailed observations of the natural world around him. This work soon led to a desire to understand and predict, rather than just describe. Leonardo's tenacity and his varied interests allowed him to make important observations and discoveries in a wide range of scientific fields, from anatomy to zoology. His studies of the motion and the behavior of fluids (such as water) were impressive. He investigated plants, animals, and geology. In addition, Leonardo made notes on astronomical topics, such as the nature of the moon, sun, and stars, and fossil formation.
Although Leonardo's observation-based method seems simple to us today, his technique was revolutionary in his day. He would ask a seemingly simple question, such as “How do birds fly?” and then spend weeks or months making painstaking observations. These observations would include watching birds in flight, sketching birds in various poses, observing live birds close-up, and dissecting birds to understand their musculature and anatomy. He then translated his notes into a more general theoretical understanding of aerodynamics and flight. Leonardo, being the hands-on guy that he was, then designed flying machines that would give humans the same experience as birds.
Leonardo also pioneered the technique of scientific illustration. While we take for granted the technical drawings that appear in our textbooks, we really should thank Leonardo for coming up with this idea. He filled many of his notebooks with meticulous sketches, accompanied by detailed notes, of various anatomical or mechanical principles. Unlike his predecessors, who relied on long-winded explanations, Leonardo felt that his sketches and drawings were the primary tool in illustrating his various points; his written notes were actually secondary. Sometimes a picture really is worth a thousand words!
48
Love that body!
Leonardo da Vinci was a man who could appreciate a great body. And all in the interest of science, really! During his lifetime, the field of medicine was becoming more important, and artists were increasingly fascinated with drawing the human body accurately. In Leonardo's case, he went a step further to figure out how the bodily systems beneath the surface worked. Leonardo's early paintings were studies in a new humanistic style of art, and he was way ahead of his contemporaries in this regard. The best example is his Vitruvian Man drawing of 1490, one of the first accurate expressions of the relationship between the human form and geometrical proportions. Leonardo's interest in anatomy ran deep, both literally and figuratively. He spent years researching the intricacies of how our bodies function. In 1489, he started work on a notebook focused specifically on anatomy. He studied all parts of the body, especially the brain and eyes. He sketched skulls in cross-section, showing both an amazing understanding of the visible and an interpretive ability to figure out the unknown. His drawings demonstrate a clear relationship between eyes, nose, teeth, jaw, and vertebrae. To make things clearer, he detailed most sketches with notes and measurements—almost like an architect doing construction documents. Many of Leonardo's other sketches define human anatomy with an unprecedented degree of detail. His drawings of the human ribcage, spine, and coccyx are highly accurate. He also rendered sketches of nudes in various positions, indicating a significant understanding of how the human form worked in motion.
Also, as the doctors of the day were only starting to realize, the best way to truly learn about the inner workings of the human body was, simply, to take a look inside. In order to study musculature and bone structures in the arms, legs, and other body parts, Leonardo dissected corpses in the early 1500s, possibly including a homeless woman who had been about nine months pregnant at the time of her death. One of his sketches shows a human fetus, complete inside a woman's body with placenta and uterus. Leonardo's drawings describe a curled fetus and umbilical cord as they lay inside the womb. However, in his drawings the unborn baby is a highly muscular infant. From this error, we can see that his factual knowledge was probably minimal. Despite some mistakes, Leonardo was one of the first to draw the female reproductive system accurately, and his drawings are certainly the most detailed to come from the Renaissance period. He also drew detailed sketches of other systems and organs, including the human heart.
Leonardo's work, detailing the nature of organs that had been previously undefined, was quite daring for the time. Renaissance clergy and others were of the mindset that the heart was some sort of spiritual element, not just a muscle like any other in the body. Although Leonardo explored science in rational, realistic terms, he did not dismiss spiritual notions. He always acknowledged the divine in his scientific studies, marveling at the complex beauty God had created.
49
From the inside out: Studies of human systems
Leonardo never stopped trying to learn more about the human body. You might even call him art's first forensic scientist. Not content just to draw the body as he saw it from the outside, he strove to understand the human form from the inside. How far would he go to increase this understanding? Farther than was acceptable or even legal at that time. He cut up cadavers, studied organs and skeletal substructures—all in an effort to draw and paint more accurately. Circulation and musculature systems intrigued him for the same reason. But what mattered most to Leonardo was the quality of his work, and he was willing to get his hands dirty—literally—to ensure that quality.
It wasn't just the body itself that interested Leonardo; he plunged deeper inside to study blood circulation and the heart, first in the 1490s, and again about twenty years later when he produced many drawings that detailed human circulation. Leonardo never figured out the exact connection between blood flow and the heart muscle, though. He used his studies of animals (and later, humans) to map out the basics: The heart was a four-chambered muscle somehow connected to the pulse you could feel in your wrist. Leonardo also figured out that arteries could become overfilled and that this situation could lead to sickness or even death. And so he actually predicted the concept of clogged arteries—an ailment that would become a major medical focus in later centuries.
Leonardo also paid particular attention to musculature, as we can see in several of his sketches. Some of his earlier anatomical drawings show extremely muscular men (perhaps indicating his own preferences), while later sketches focus more on anatomical detail. A series of shoulder drawings from 1511 show tremendous schematic detail on the layering of bodies, depicting skin, bone, muscle, and surrounding tissue as a complex web. Leonardo's paintings from twenty years earlier show this same fascination with the muscle groups, which create sculpted definition.
And now on to the fun stuff—sex! Leonardo was very interested in human reproduction. He initially thought the male reproductive organs had a direct channel that went straight to the heart and lungs and, therefore, the brain. (Hippocrates, a Greek physician from the fifth century B.C. and one of the founders of modern medicine, originally suggested these views.) As mentioned earlier in reference to the heart (see number 48), the popular view during the Renaissance was that bodily organs represented divine, spiritual entities. In keeping with this tradition, Leonardo considered the main outputs of the male sex organs as, essentially, sperm and “spirit.” He also believed the human heart was a spirit. Nice idea, but he quickly realized that this approach was wrong because it could not be proven. The idea of a “spiritual channel” could simply not be bor
ne out by the cold, hard evidence that Leonardo personally witnessed. At least Leonardo was willing to admit when he made a mistake—wouldn't it be nice if everyone did?
50
Fawning over flora
Leonardo began his long history of drawing animals by studying them in nature. Many of his paintings show different animals, some moving and some standing still. The Adoration of the Magi, for example, includes horses, a camel, and a mysterious third creature that Leonardo never finished. He also sketched an iconographically significant lamb in The Virgin and Child with Saint Anne (see number 39), though he himself may not have painted that particular portion of the work.
The horse was one of Leonardo's favorite animals. We know about his obsession with them because they're the animal he sketched the most. He drew them standing, sleeping, and in various states of motion. His Statue of Francesco Sforza (see number 29), if completed, would have been the largest monument of a horse anywhere in Europe. Toward the end of his life, Leonardo also made many bronze horse models that he gave to his final patron, King François I.
Leonardo's notebooks also prominently feature cats. He wrote stories about cats and sketched them in precise detail. He drew felines in a variety of positions, both asleep and in motion. Leonardo gave a cat the central focus in at least one of his paintings, The Madonna with the Cat. Leonardo also painted other animals at different points throughout his career, including pigs, bears, goats, birds, and dragons. There are also drawings of several animals that look like either crossbreeds or completely fictional beasts.
What is unique about Leonardo's drawings of animals is that he applied the same principles of geometry and proportion to them as he did to his architectural drawings. He made notes, for example, about how a horse's ear should be one-fourth as long as its face. He also studied the movement of birds in flocks and tried to rationalize their tendency to fly in circles. When he wanted to paint animals as accurately as possible, Leonardo knew that he would have to learn more about how their bodies functioned. His notebooks tell us that he made several visits to slaughterhouses. His sketches contain studies of dissected animals, including some highly detailed drawings of pig hearts. Once he revealed the animal's innards, Leonardo was able to see the still-beating heart and observe how blood was moving out of the heart and through the arteries. These scientific sketches were extremely significant because they were the first of their kind. Not only artists, but also future doctors would study Leonardo's drawings and methods as they later began their own research into anatomy.
Leonardo's interest in the natural world spread to flora as well as fauna. Unfortunately, Leonardo's plant sketches are some of the worst preserved of any of his drawings. We do know he drew lots of plants because his first biographer, Giorgio Vasari (1511–1574), tells us so. One existing sketch is the Star of Bethlehem, which was created between 1505 and 1507. This sketch is significant because, in addition to being one of his few surviving plant drawings, it shows a highly stylized, abstract flower. In contrast, most of his earlier plant drawings were more scientifically accurate. While a single flower may not seem like such a big deal, it's important to understand that Leonardo didn't just paint what he saw—he was also very creative.
Other surviving drawings include mountainous landscapes and rivers. Leonardo made these artworks in media such as metalpoint, chalk, and pen and ink. He is also known for the detailed botanical renderings of various plants and trees that exist in some of his paintings. While many Renaissance artists focused exclusively on the painting's central figure, Leonardo paid attention to every detail, and his work is richer because of it.
51
The perfect man
One of the most famous drawings of all time is Leonardo da Vinci's Vitruvian Man of 1490 (see the cover of this book). In the original sketch, which currently resides in Venice, Leonardo used both ink and watercolor. Leonardo's image has become an icon for art, science, and the Renaissance. Today it's such a widely recognized symbol, you can see it everywhere—in high-school textbooks and museum galleries, even on T-shirts. What is it about this particular drawing that has generated such attention? What is this drawing even about?
The source of inspiration for the Vitruvian Man was, not surprisingly, Vitruvius. But who was he? He was actually a Roman engineer from the first century B.C. who codified some of the first basic principles of architecture. Serving as chief architect under Julius Caesar, Vitruvius was ancient Rome's resident expert in urban planning and structural design, and he wrote the first definitive treatise on architecture, The Ten Books on Architecture (around 27 B.C.), in which he specified guidelines for city planning, building materials, hydraulics, and other civic projects. This influential book also established differences for religious, private, and public designs—the first time that such distinctions had been laid out so clearly. In addition to providing rules and principles for architects to follow, Vitruvius expressed the important relationship between architecture and social-cultural values.
It is likely that Leonardo's first exposure to Vitruvius, and his ideas on form and proportion, came during his apprenticeship to Verrochio. He was also probably influenced by Alberti's interpretations of the same subject. But Leonardo, as usual, came up with his own radical uses and interpretations.
In fact, Leonardo's Vitruvian Man could have been a poster child for Renaissance ideals of humanism and proportion. The drawing consists of a square that is partially inscribed in a circle, with a human male form inscribed into the combination of these two basic geometric shapes. This drawing has become so celebrated because it's the first example of a human form that wasn't forced into an unnatural distortion simply to accommodate the geometry.
Architecture, for Leonardo and most Renaissance architects, was a matter of harmonious modularity. As Leonardo proved with this drawing, it was possible to view the human body the same way: a composition of anatomical building blocks comparable to those of the built world. Interestingly, it's been said that in a not-so-rare moment of artistic hubris, Leonardo may have borrowed his own self-portrait to use for the head of Vitruvius in this influential work! Doesn't it seem appropriate, though, that Leonardo himself might be both model and artist for this symbol of the Renaissance?
52
Getting physical with science
Leonardo did more than draw circles and squares! Sure, he studied anatomy, but his interest in science didn't end there. He was also a student of the physical and natural sciences. In particular, he used his methods of observation and inquiry to look at a number of problems in physics, geology, astronomy, and other fields.
In geology, Leonardo's contribution is particularly striking. While working as part of Duke Sforza's court, Leonardo devoted time to surveying various mountains and valleys, and this work served as background for military engineering projects, such as making roads and tunnels. During this period, Leonardo most likely had ample time to study the area's various rocks, and he also observed the fossils (mostly mollusk shells) present within the rocks. From his writings, we know that Leonardo understood the process of sedimentary rock formation, which occurs through sequential deposition of small layers in a watery environment. He also understood erosion, the idea that wind, rain, and rivers progressively wear away rocks. In fact, he realized that, as a result of erosion, sand and rock particles are eventually carried to the ocean to repeat the cycle.
How is it that shells could be found in rocks that currently lay atop mountains? Scientists pondered this central geological question in Leonardo's day, and Leonardo rejected the two main suggestions prevalent at that time, which held that the shells had either been carried there by the great flood mentioned in the Bible, or that they had formed there in the rocks. From his observations of nature, Leonardo knew that shells had to come from living creatures and that these living creatures would have had to move around to eat and grow—they couldn't have formed inside a rock. He also noted that the world probably wasn't ever covered by a single great flood, since the water
wouldn't have had anywhere to drain. Even if a flood had taken place locally in biblical times, any shells carried up to the mountaintops would have formed a jumbled mess, not the orderly layers that Leonardo saw.
Remarkably, Leonardo's solution to this puzzle came very close to the modern understanding. He suggested that when the fossils had been living sea creatures, they had been in an ocean environment. At some later time, mountains formed, and their gradual formation lifted the ocean sediments up to the mountain peaks. In fact, we know today that this model is a pretty good approximation of what actually happened!
But Leonardo didn't have the same good luck with all of his scientific theories; some of his beliefs were just wrong. In the field of astronomy, for example, Leonardo seemed to think that the sun and moon both orbited around the earth, and that the moon reflected the light of the sun because it was covered with water. Although he tried his best and did conduct some experiments with optics and lenses, telescopes were not invented until 100 years after Leonardo's time.
According to a sketch from 1510, Leonardo did manage to calculate a way to determine the distance from the earth to the moon, and the earth to the sun. He was also apparently one of the first to realize that even when only part of the moon was lit, the dark part of the crescent moon could still be seen faintly. (This illumination comes from sunlight that bounces off the earth and is then reflected off the moon.)
Clearly, while some of Leonardo's achievements in science were noteworthy, others weren't. Looking back, you could say that Leonardo's theoretical studies were generally less important than his practical innovations. However, you can also see that his inventions allowed Leonardo to discover and pursue new theoretical lines of research. Even modern scientists often need both theories and experiments to make breakthroughs!