by Rob Dunn
Da Vinci appears to have found a strong supporter in the cardinal, a supporter not for his art but, amazingly, for his science. Da Vinci might have gone home to finish the document he showed the cardinal, but unknown to the cardinal, da Vinci had already suffered a stroke. If it was like many strokes, a piece of plaque, secondary to atherosclerosis, was freed by chance movements of blood and the pressure of his beating heart and sent, perhaps along with clotting blood, into the narrow vessels of his brain. There, it wreaked havoc. Da Vinci could no longer move his hand. He would write and draw no more. He died a year later (possibly of another stroke). Whatever book existed was never finished, his knowledge lost except for what remained among his notes.
After da Vinci’s death, one of his pupils, Francesco Melzi, began to try to produce from da Vinci’s writings a version of the long desired treatise on anatomy. Melzi worked his entire life on the project, attempting to simply restate and convey what da Vinci had discovered. But it was too great a task. Da Vinci wrote backward on the page, having taught himself to write, and Melzi had to teach himself to read backward. But this was not the only problem. Da Vinci also made up words, fused words into unusual compounds, broke ordinary words into pieces for no apparent reason, and never used punctuation. (All of this suggests that whatever the cardinal read was something more polished than da Vinci’s notes.) But there was actually an even bigger problem. In reading da Vinci now (in translation and from left to right), we understand his insights, but to his contemporaries, the most interesting of his discoveries were too radical. It has been speculated that Melzi struggled to distinguish the bits of da Vinci’s work that seemed to be the spouting of a madman from those that were genuine discoveries. Whereas da Vinci had pushed the envelope of science with confidence without, apparently, caring what his colleagues thought, Melzi cared. He did not want his mentor to seem ridiculous. He knew that much of what da Vinci wrote was genius, but was it all? He couldn’t tell. As a result, he never finished. When Melzi died, in 1568, da Vinci’s notes (at least the five thousand sheets Melzi had) were still in disarray. Melzi had compiled more than nine hundred chapters based on the notes, but they were a mess, a failed attempt to understand the man who had discovered more than anyone before. There was never to be a great da Vinci book of anatomy. Instead, da Vinci’s contributions to science, so close to transforming human understanding, were simply and progressively lost, not to be seen again until after his biggest discoveries were made anew by other scientists.
Surely, da Vinci discussed his insights with his colleagues.14 He must have shown off some of his drawings. One does not dissect an old man without at least mentioning it in conversation to friends over wine, which da Vinci purchased in huge quantities, according to the grocery bills of his that historians have compiled. You would not believe his arteries, we might imagine him saying, but we can only imagine. In the decades after da Vinci’s death, his notes disappeared both physically and from discussion. Some may have been destroyed. Others were turned over to colleagues such as Melzi, to wealthy families, and to religious leaders. Some of these notes would be rediscovered and translated in the late 1800s. Others waited until the 1960s. Many of da Vinci’s contributions may still be missing. As a result, da Vinci’s greatest insights—about the flow of blood, atherosclerosis, and the working of the heart’s valves—were hidden and so seem to have played little or even no role in the rebirth of knowledge about the heart. Da Vinci was, ultimately, “a man who awoke too early in the dark.”15 As the scholar Kenneth Keele wrote, “His gigantic efforts in the realm of what we now call science tragically failed to disturb his fellows from their slumbers.” If he had any influence at all on the science that followed him, it was likely due to his art rather than his careful dissections. In the Mona Lisa,16 The Last Supper, and every other painting by da Vinci, art patrons find greatness in the consequence of brushstrokes. It is a greatness of paint built on the scaffolding of da Vinci’s understanding of flesh and bones and even the vital beating heart.
4
Blood’s Orbit
Andreas Vesalius was just nineteen years old when he left Belgium. It was 1533, and he believed himself destined for greatness. He considered, very briefly, where he might go to best attain this greatness, and without a doubt, there was but one place: Padua, Italy. In Padua, science was being reborn. There has never been a more important place in the history of science, particularly medicine, than Padua and probably never a more important time than the decades in which Vesalius lived there. Vesalius would go to Padua to be great.
Padua is located in what is now Northern Italy, but when Vesalius arrived, it was a small city in the kingdom of Venice. In Venice, the doge—the leader of the republic—was a kind of god-king in a silk gown and triangular hat. In the late 1400s and early 1500s, a succession of doges, along with wealthy community leaders, sought to make Venice a scientific power by funding education. Venice was already a maritime and military power. Venice was mighty, and soon it would indeed be scholarly too. By the mid-1500s, after da Vinci’s death, eager young philosophers—anatomists included—began to flock to the city. As they did, Padua’s reputation spread.
Vesalius imagined he would find this flourishing greatness in Padua, and in some fields, it was indeed present, but not, from Vesalius’s perspective, in anatomy. In Padua, anatomy theaters seemed to be more like circuses than temples of knowledge. Dogs crawled beneath bodies; everything stank of rot. But what was worse, at least to Vesalius, was the response of the students and professors. Vesalius expected them to look eagerly at the bodies before them, greedy for new understanding. Instead, they looked away. In the dark basement of the Hospital Dieu, for example, Vesalius watched as a professor read from a book while one assistant dissected the body and another held aloft or pointed to the relevant parts. Nothing was being illuminated, not the body’s features and definitely not the truth. This was twenty years after the death of da Vinci, and yet nearly every one of his lessons seemed to have been lost.
The science Vesalius found was not real science; it was a kind of education masquerading as science in which anatomists demonstrated the knowledge acquired centuries before rather than attempting to reveal new truths. This form of educational anatomy had its formal origins in 1315. A woman from Bologna was sentenced to death and executed; a professor, Mondino de Liuzzi, retrieved her corpse and, with the Vatican’s blessing, began to cut into it in order to teach his students about the body. When earlier dissections had been performed, they were done with the goal of autopsy. In one episode in 1286, for instance, a disease of some sort struck down hundreds of chickens and people in Cremona, Parma, and neighboring towns. In order to ascertain the cause, many chickens and several humans were dissected. What was found was described as a sort of boil or bump on the heart, which is hard to interpret in terms of modern medicine. This was enough to lead to a local pronouncement that no one should eat chickens or eggs,1 but it, like other autopsies, produced little in the way of formal education or new science. With Liuzzi’s dissection, however, informal procedures for dissections began to be established. Each would last four days, after which point the smell of the body would simply be too awful for anyone to continue. Dissections would be held once or twice a year using the bodies of criminals, such as the woman from Bologna, and the body was to be fully dissected. (This differed from previous dissections, which tended to attempt to preserve the form of the body so that the family might still visit the corpse after the dissection.) On the basis of these educational events, Liuzzi wrote Anathomia, the first real book about the existing knowledge of dissection and anatomy. The goal of Liuzzi’s book, just as for the dissections themselves, was not science as we know it today; it was, more simply, to reveal and educate. His book was a textbook, and to the extent that advances were made, they were advances in how to perform a dissection, not in the biology of the body. The dissection when done perfectly did not reveal truths. It revealed God. Later, when cuts into the heart uncovered only muscle where God mig
ht have been expected, the dissections revealed the knowledge of Galen. Even this revelation was imperfect. Liuzzi’s book contained a less accurate depiction of the anatomy of the heart, for example, than did Galen’s work more than a thousand years before. This was the tradition of academic dissections; it was a tradition far different from that in which da Vinci thrived, a tradition focused on rediscovering the past in each of its details, however flawed.
At first, Vesalius obeyed the norms of this culture, of looking and learning, but eventually, he became too frustrated. He wanted to discover, and he knew that discovery was far from over. More must lurk in the organs than had been revealed. He began to do his own dissections, apart from Liuzzi’s traditional two a year. In doing so, he was, at least by his own accounting, the lone learned man actually studying the gore of the flesh. His colleagues discouraged him, and he was threatened (physical fights were not uncommon among anatomists). He bit the hands that trained him. He accused his mentors of “never having lifted a knife except to cut a steak.” He cut one body and then another, and as he did, he tried to understand what others had missed, about the heart, about everything, building up personal knowledge from cadavers, wresting discovery from decay.
Vesalius had to cut into a large number of bodies both to see what was present and to understand whether what he had seen was normal, the state of the average body rather than some exception. But he also had to find bodies. Vesalius became an expert at body snatching,2 among history’s greats. He would go to the gallows himself and cut the ropes on which a man hung, letting the weight of the corpse fall against his body. He would go to cemeteries filled with the half-buried bodies of the dead. He forged keys to break into ossuaries. He and his students knew no limits in their search for the dead, a search that broke so many rules that Vesalius would, on some occasions, need to instruct his students to flay the skin of a body before beginning a dissection so that it would not be recognized by relatives searching for the missing remains of their loved one.
As he cut, Vesalius began to doubt more and more of the wisdom his mentors had handed down to him. Some of these concerns he came up with on his own. Others might have trickled down through other sources, even possibly from da Vinci. Despite their never having been published, da Vinci’s observations might still have had some influence, perhaps by word of mouth or even in the form of an unofficial manuscript of some sort. Writing fifty years after the death of Leonardo da Vinci, Giorgio Vasari (the great and sometimes accurate biographer of the Renaissance artists) noted that Vesalius “was wonderfully aided by the talent and labor of Leonardo, who made a book drawn with red chalk and annotated with the pen of the subjects which he dissected.” We can’t be sure what exactly these red chalk drawings included, or that they existed, or that Vesalius saw them, and yet the possibility of a connection between the two men cannot be ruled out. We do know that if Vesalius did see these drawings, they could not have been very complete, since most of what da Vinci discovered would ultimately be missed by Vesalius. Vesalius also made some discoveries that da Vinci missed.
One of Galen’s certainties that bothered Vesalius was the claim that blood moved through pores from the right to the left side of the heart. Vesalius cut hearts regularly. He did not see pores; he saw only the thick muscular wall separating the left and right ventricles. Da Vinci had never commented on the pores. To Vesalius, if such pores existed, they were invisible. Or else Galen was wrong. It was still taboo for anyone to openly discuss the problems in Galen’s texts. But Vesalius had had enough. Emboldened by frustration, Vesalius wrote the sort of book da Vinci should have written—now considered the most important book in the history of medicine.3
In this book De Humani Corporis Fabrica (On the Fabric of the Human Body), Vesalius revealed the body anew. In describing the book (published in 1543), scholars often note that Vesalius corrected more than two hundred errors in Galen. This is true—sort of. The book was an act of defiance, and it corrected much that was wrong in Galen, but in many cases, it did not do so through the words of Vesalius. The revolution Vesalius led was subtler.
When Vesalius wrote his big book, he had no trouble finding an artist willing and able to depict the body. The artist’s identity continues to be debated, but evidence suggests it may have been the great Titian himself or, if not Titian, an artist from his school. Titian (1488–1576) was the most renowned painter in Venice in the early 1500s. He was, relative to his contemporaries, “the sun amidst small stars,” and he shone for both his use of color and his depictions of human bodies in movement. (Note: His sun shines on. One of his paintings was recently purchased for seventy-one million dollars.)
Whoever the artist was, he drew upon the techniques of Venice and Florence and, especially, da Vinci, including his use of red chalk. Here was, perhaps, a creeping but woefully modest influence of da Vinci by way of his impact on the art of Florence. Vesalius had Titian or someone from his school, someone with a hint of da Vinci’s style, depict the body as he, the artist, saw it, although tempered by Vesalius’s interpretation. It was in these depictions that the body’s realities most clearly deviated from Galen’s teachings. Vesalius did not have to say what was wrong with Galen’s work if the artist could show it. For Vesalius, as Arturo Castiglioni put it, anatomy “evolves with drawing, for drawing and through drawing. The need of texts was no longer felt so much as the need of pictures,”4 radical pictures.
Even this subtle rebellion against tradition was not well considered. Vesalius’s own teacher Sylvius said of him that he was “an impious madman who is poisoning the air of Europe with his vapourings.” To that comment and the many others like it, Vesalius grumbled, “Professors think it beneath their dignity to take a knife in hand.” But all that was beginning to change. Vesalius had stormed the hill. It was just a matter of time before a few others tumbled over, though perhaps more time than Vesalius might have guessed.
Why was Vesalius, after fourteen hundred years, able to see (some of) the errors in Galen when everyone else had missed them for more than a thousand years and for more than fifty years after da Vinci? Partly, it was the bodies themselves: having them and having so many of them. It was also his prepared mind; he was blessed with unusual powers of observation. Others were beginning to see partially what he was seeing most clearly. But art too was key. Art was the tool with which Vesalius could see and show both the heart and, in great detail, the arteries and veins, including the very first drawings of the valves in veins. Once Vesalius had shown the heart, more discoveries became inevitable. Vesalius revealed Galen’s knowledge to be incomplete, and when he did, other anatomists looked to Fabrica and wondered what else had been missed.
The next advance after Vesalius was that of one of his students, Hieronymus Fabricius. Fabricius accurately noted that there were small valves throughout the veins. To Fabricius, the valves seemed to block the flow of blood out through the veins toward the extremities. He was wrong. He, like all those before him, did not understand that blood goes only one way through the veins: to the right side of the heart (the exception is the pulmonary vein, which takes oxygenated blood from the lungs to the left side of the heart). Because he didn’t know which way the blood moved, he could not quite make sense of the valves. Yet the observation of the existence of the valves was to prove very important.
The work of Vesalius and then Fabricius combined with the wealth of Padua attracted even more scholars from around the world. They brought with them new ideas and perspectives, and they took home with them new insights. It was to Padua, Fabricius, and the operating theater in Padua called the Bo, in which dissections had become grand public performances, that a young man named William Harvey would eventually come for the education that would help him make what has been called the single largest discovery in the history of the human body. There, the young Harvey would hear from great minds like Fabricius as he looked down upon stinking bodies, their parts emerging and disappearing in the flicker of the candlelight that bathed the theaterlike roo
m. It would be enough light, though just barely, to see big, holistic truths.
William Harvey was born in 1578 (some thirty-five years after the publication of Vesalius’s De Humani Corporis Fabrica) to a working-class family in Kent, England, where his chances of achieving intellectual greatness seemed slim. He was not a noble, and only nobles had access to the best schools. But precisely at the time that Harvey was readying himself for school, things began to change. For reasons of politics and, again, economics, the educational system had started to open up, which allowed young William to go to a better school than he might have otherwise—a school that, if he succeeded there, could allow him to go anywhere, even college.
Early on in his education, Harvey did not seem marked for greatness. He was not the smartest boy in his classes. But he had one advantage over his peers. While they were brought up in affluence and given what they asked for (including their education—a fancy degree was no guarantee of any sort of real academic accomplishment), Harvey had to work for his successes. Just as his father worked hard in day labor, Harvey would work hard at his education. It was not an avid striving so much as it was young Harvey’s understanding of what one should do. One must work, and so he worked. He worked hard at school and studied, and when he was done studying, he studied some more.
William Harvey, the man who revealed how blood circulates through the body and, in doing so, reordered our understanding of each human organ. (Courtesy of the National Library of Medicine)
