The Science of Leonardo: Inside the Mind of the Great Genius of the Renaissance

by Fritjof Capra

  Oil painting is said to have been invented by the Flemish master Jan van Eyck. According to Vasari, the technique was introduced in Italy first in Naples, Urbino, and Venice before eventually reaching Florence, where it caused a sensation. When Leonardo was an apprentice in Verrocchio’s workshop, the Tuscan painters had not yet fully mastered the technique of oils. Leonardo became a major figure in its perfection, together with his fellow student Perugino, who passed their secrets on to Raphael.42

  Over the years, Leonardo achieved a sublime mastery in applying the finest layers of paint to create the luminous color tones that give his paintings their special magic. As Serge Bramly describes it, “The light passes through his paintings as if through stained glass, straight on to the primed surface beneath, which reflects it back, thus creating the impression that it emanates from the figures themselves.”43

  The slow and careful process of painting that is required by oils was ideal for Leonardo’s approach. He could spend weeks between layers of paint, and could rework and refine his panels for years, reflecting on every detail of their conception, engaging in the mental discourse that he saw as the essence of his art and science. This discorso mentale, the intellectual process of painting, was often more important to Leonardo than the actual completion of the work. Consequently, the total output of his life as a painter was relatively small, especially in view of the profound impact he had on the subsequent history of European art.

  On the other hand, Leonardo’s completed masterpieces always involved radical innovations at several levels—artistic, philosophical, and scientific. For example, the Virgin of the Rocks (Fig. 2-4) was not only revolutionary in its rendering of light and dark. It also represented a complex and controversial meditation on the destiny of Christ, expressed through the gestures and relative positions of the four protagonists, as well as in the intricate symbolism of the surrounding rocks and vegetation.44

  Figure 2-4: Virgin of the Rocks, c. 1483–86, Musée du Louvre, Paris

  The rocks themselves are rendered with astounding geological accuracy. Leonardo depicted a complex geological formation involving soft, weathered sandstone dissected by a layer of harder rock known to geologists as diabase. Numerous fine details in the rocks’ textures and weathering patterns show the artist’s profound knowledge, unmatched in his time, of such geological formations.45 And finally—in a dramatic departure from the traditional decorative use of plants in the quattrocento—the plants growing in the surroundings of the rocky grotto are rendered not only in exquisite botanical detail but also in their proper habitat, with complete seasonal and ecological accuracy.46

  Observations of similar innovations can be made in The Last Supper, the Mona Lisa, or the Madonna and Child with Saint Anne. It is no wonder that each of these masterpieces caused great commotion among Leonardo’s contemporaries, generating animated discussions and numerous copies, which expanded the master’s discorso mentale throughout Europe’s artistic and intellectual circles.

  IL CAVALLO

  In the “Paragone,” Leonardo introduces one of his lengthy arguments about the superiority of painting over sculpture with the following self-assured words:

  As I apply myself in sculpture no less than in painting, and practice both in the same degree, it seems to me that without being suspected of unfairness I can judge which of the two is of greater ingenuity and of greater difficulty and perfection.47

  In a similar vein, Vasari refers to Leonardo as “Florentine painter and sculptor” in the title of his biography. And yet, we have no known sculpture from Leonardo’s hand. His reputation as a sculptor rests on a single piece of work: a monumental bronze horse that was never cast, but which occupied Leonardo intensely for over ten years.

  When he was in his late thirties and employed as “painter and engineer” at the court of Ludovico Sforza in Milan, Leonardo received a commission for an equestrian statue honoring the duke’s father. The city’s tremendous wealth at the time encouraged grandiose schemes, and accordingly Ludovico wanted the equestrian monument to be grandissimo, perhaps three or four times life-size. A bronze sculpture of that size had never been attempted before. The unprecedented challenges of the project fascinated Leonardo, and even though he was generally not fond of sculpture, he eagerly accepted the commission. It was a project that would draw on his scientific interests in anatomy, proportion, and the animal body in motion as well as his engineering skills and artistic talent. Beautifully told by Serge Bramly in his biography Leonardo: Discovering the Life of Leonardo da Vinci, the episode is closely linked to the fluctuating fortunes of the Sforza dynasty.48

  At first, Leonardo considered a horse rearing over a vanquished enemy. The forceful vitality of that image appealed to him, but the structural problems turned out to be forbidding even for his genius. How could he create a horse weighing many tons that could stand on two legs? Even if he created additional support by making one of the forelegs rest on the vanquished enemy, how could he cast and balance the entire group? After a long and careful examination of these staggering technical difficulties, Leonardo abandoned the idea of a rearing horse and eventually settled on the classical pose of an antique equestrian statue, known as the Regisole, which he had greatly admired in Pavia.49 He had been especially impressed by the statue’s natural grace. “The movement is more praiseworthy than anything else,” he jotted down in his notebook. “The trot almost has the quality of a free horse.”50

  While he pondered various poses of the bronze horse and the associated engineering problems, Leonardo seemed to have completely forgotten its rider. The statue of Duke Francesco, clad in armor, was to be cast separately and added later, but over the years Leonardo became so absorbed by the physical beauty, proportions, and movements of the horse that he referred to the monument simply as il cavallo.

  Once he settled on the final pose of the horse, Leonardo repeatedly visited the princely stables of Ludovico as well as those of other wealthy Milanese noblemen in search of models for his cavallo. He identified several superb thoroughbreds, measured them meticulously to determine their proportions, and drew them from life in numerous positions. In typical fashion, he got carried away with the intellectual aspects of the undertaking, expanded it into a major research project, and ended up with a full treatise on the anatomy of the horse.51 In addition, he produced a wealth of artistic studies of horses, now assembled in a special volume of the Royal Collection at Windsor Castle. In the opinion of art critic Martin Kemp, “No one has ever captured more convincingly the rippling beauty of a finely bred and groomed horse.”52

  Finally, after four years of preparatory studies, Leonardo built a full-scale model of the sculpture out of clay. At a height of slightly over twenty-three feet, it towered over the most famous equestrian statues of the time—that of Marcus Aurelius on the Capitol in Rome, Donatello’s Gattamelata in Padua, and Verrocchio’s Colleoni in Venice. Not surprisingly, the colossal model generated enormous excitement when it was displayed in front of the Sforza castle on the occasion of the marriage of Ludovico’s niece Bianca Maria to the emperor Maximilian. “The vehement, life-like action of this horse, as if panting, is amazing,” wrote Paolo Giovio, “not less so the sculptor’s skill and his consummate knowledge of nature.” Vasari claimed that those who saw the clay model felt that they had never seen a more magnificent piece of work. The court poets composed Latin epigrams in praise of the gran cavallo, and Leonardo’s fame as a sculptor soon spread throughout Italy.

  While completing the model, Leonardo thought deeply about the tremendous challenge of casting such a large piece. He collected all his notes on the subject in seventeen folios of a book (now bound at the end of the Codex Madrid II), beginning with the words: “Here a record shall be kept of everything related to the bronze horse presently under construction.”53

  The traditional method of casting was to divide the work into several smaller pieces to be cast separately, but Leonardo concluded that it would not be possible to make all the pieces of unif
orm thickness. As a result, he would not be able to estimate their weight and establish in advance the overall balance of the sculpture. Having investigated all aspects of the problem with his usual attention to meticulous details, he decided to cast the horse in one piece, something that had never been attempted before. His voluminous notes have allowed art historians to reconstruct Leonardo’s method in detail.54 It involved digging a huge pit to bury the mold upside down, so that the molten metal could run in through the animal’s belly while the air escaped upward through the feet.

  Leonardo left very detailed and beautiful drawings of the iron framework he had designed for the horse’s head and neck, held in place by an ingenious set of hooks and wires. Other drawings show the wooden frame he intended to build for transporting the giant mold, as well as the elaborate machinery for maneuvering it. His descriptions cover every conceivable aspect of the casting process—from recipes for alloys and methods for controlling the temperature in the furnaces to dress rehearsals with small-scale models.

  By early 1494, everything was ready for the casting. The materials had been acquired, and a start was probably made on digging the pit and building four specially designed furnaces around it. But then political necessity intervened. During the previous two years, several Italian political leaders had died, European alliances had shifted, and now Charles VIII, the new king of France, was about to attack Milan. Under this imminent threat, Ludovico decided to use Leonardo’s precious seventy-two tons of bronze for new cannon instead of the gran cavallo. Leonardo remained optimistic that he would be able to proceed eventually, and continued to work on his project. But Ludovico ran out of money. It became clear that the glorious monument would never be cast. About a year later, Leonardo attached a simple note to a letter he had written to the duke: “About the horse I will say nothing, for I know the times.”55

  Leonardo’s molds were never used, and his giant clay model eventually crumbled and decayed. His fame as a sculptor, however, lived on, as did his novel method of casting. Two hundred years later, it was used in France to make an enormous equestrian statue of Louis XIV, almost as tall as the gran cavallo. “Even the stance of the horse was the same,” Bramly tells us, “and by remarkable coincidence, the same bad luck attended the statue: it was destroyed during the Revolution, so we cannot see it. But the fact that it was cast at all shows that [Leonardo’s] method was sound.”56

  LEONARDO THE DESIGNER

  Upon reflecting on the great diversity of Leonardo’s interests and pursuits, virtually all those that cannot be seen strictly as “art” or “science” may be subsumed under the broad category of “design.” The notion of design as a distinct discipline emerged only in the twentieth century: As a result, viewing Leonardo as a designer means applying a modern category that did not exist in his time.57 Nevertheless, it seems intriguing to examine his wide-ranging pursuits from our contemporary perspective.

  Design, then and now, has always been an integral part of a larger process of giving form to objects.58 At its outset, the design process is purely conceptual, involving the visualization of images, the arrangement of elements into a pattern in response to specific needs, and the drawing of a series of sketches representing the designer’s ideas. All these are activities that fascinated Leonardo and in which he excelled.

  As the design process matures and moves closer to the implementation phase, its dependence on other disciplines increases. Hence, we classify different types of design according to the domains in which they operate. Today’s design disciplines include those associated with civil, military, and mechanical engineering; architectural design; landscape and garden design; urban design; fashion and costume design; stage and theatrical design; and graphic design. Leonardo da Vinci was active in all these “design disciplines” throughout his life.

  Good designers have the ability to think systemically and to synthesize. They excel at visualizing things, at organizing known elements into new configurations, at creating new relationships; and they are skillful in conveying these mental processes in the form of drawings almost as rapidly as they occur. Leonardo, of course, possessed all these abilities to a very high degree. In addition, he had an uncanny knack of perceiving and solving technical problems—another key characteristic of a good designer—so much so, in fact, that it was almost second nature to him.

  Many of the machines and mechanical devices he drew were not original. But when he took them from sketches of earlier inventors, he would invariably modify and improve their design, often beyond recognition. When he worked on the large cartoon of The Battle of Anghiari, he constructed an ingenious scaffolding, according to Vasari, “which he could raise or lower by drawing it together or extending it.” While he spent long hours in the Sforza stables drawing thoroughbred horses from life, he also designed and sketched a model stable featuring automated supply lines of fodder and water as well as runoffs for liquid manure, which would provide the basis for the Medici stables twenty-five years later.59 Whatever he was engaged in, technical innovations were never far from Leonardo’s mind.

  FROM ENGINEERING TO SCIENCE

  It was during his employment as “painter and engineer” at the Sforza court that Leonardo’s technical inventiveness came into full bloom. The duties of an artist at a Renaissance court included, besides painting portraits and designing pageants and festivities, a variety of small engineering jobs that demanded unusual ingenuity and skills in the handling of materials.60 Leonardo’s many creative talents were perfectly suited for this. He invented a large number of astonishing devices during this time, which brought him considerable fame as an engineer-magician.

  Many of these inventions were extraordinary for the period.61 Among them were doors that opened and closed automatically by means of counterweights; a table lamp with variable intensity; folding furniture; an octagonal mirror that generated an infinite number of multiple images; and an ingenious spit, in which “the roast will turn slow or fast, depending upon whether the fire is moderate or strong.”62 Other inventions of a more industrial nature included a press for making olive oil, and a variety of textile machines for spinning, weaving, twisting hemp, trimming felt, and making needles.63 Leonardo remained an avid inventor throughout his life. The total number of inventions attributed to him has been estimated at three hundred.64

  But this combination of artist-engineer was not unusual in the Renaissance. Leonardo’s teacher Verrocchio, for example, was a renowned goldsmith, sculptor, and painter as well as a reputable engineer. The great Renaissance architect Brunelleschi was trained as a goldsmith and first gained notice in Florence as a sculptor. Later on, when he was famous as an architect, he was also acclaimed for his inventive genius as an engineer, both civil and military. Brunelleschi died six years before Leonardo was born. The young Leonardo admired him greatly and declared his indebtedness to the great architect by drawing several of Brunelleschi’s renowned lifting devices and architectural plans.65

  What made Leonardo unique as a designer and engineer, however, was that many of the novel designs he presented in his Notebooks involved technological advances that would not be realized until several centuries later.66 And second, he was the only man among the famous Renaissance engineers who made the transition from engineering to science. Like painting, engineering became a “mental discourse” for him. To know how something worked was not enough for Leonardo; he also needed to know why. Thus an inevitable process was set in motion, which led him from technology and engineering to pure science. As art historian Kenneth Clark notes, we can see the process at work in Leonardo’s manuscripts:

  First, there are questions about the construction of certain machines, then…questions about the first principles of dynamics; finally, questions which had never been asked before about winds, clouds, the age of the earth, generation, the human heart. Mere curiosity has become profound scientific research, independent of the technical interests which had preceded it.67

  ARCHITECTURAL DESIGN

  Leona
rdo was active in the field of architecture throughout his life, but his name is not associated with any church or other building, nor is he mentioned in any architectural contract. Yet he was praised as an “excellent architect” by his contemporaries, and art historians such as Ludwig Heydenreich and Carlo Pedretti feel that he deserved this reputation.68

  In architecture, as in many other fields, Leonardo’s main interest was in design. His Notebooks are full of architectural drawings; he produced numerous designs for villas, palaces, and cathedrals, and he was often consulted as an expert on architectural problems.69 However, his drawings are not of the kind that a patron would expect from a professional architect. They are never precise proposals or detailed plans, and, as Daniel Arasse observes, they are remarkably free of “any studies of the details of architectural vocabulary (columns, capitals, frames, cornices, moldings, and so on). It is the syntax, the logical linking and the reciprocal organization of the parts of the building that interest Leonardo.”70

  In other words, the problems Leonardo addresses are theoretical problems of architectural design. The questions he asks are the same questions he explores throughout his science of organic forms—questions about patterns, spatial organization, rhythm, and flow. The notes accompanying his drawings (written in his customary mirror writing, and hence intended for himself) can be seen as fragments of a treatise on architecture that Leonardo, according to Heydenreich, may have intended to compose.71

  As a result of his unique systemic approach to architecture, Leonardo’s architectural design is characterized by a remarkable indifference to classical forms and a high degree of originality. “The solutions which he imagines,” writes Arasse, “are invariably (brilliantly) unconventional—that is to say, they are not ‘classical,’ being simultaneously Gothic in some respects and already Mannerist in others.”72