Chapter III: Front Matter (3)

Legend relates that Leonardo became so absorbed in his studies that the prior of the monastery complained to Ludovico that the “Last Supper,” although nearly completed, still lacked the faces of Christ and Judas. Ludovico summoned Leonardo to court and laid the complaint before him. Leonardo, however, was quick to reply.

“The good prior is an esteemed man, your Grace, but he is a monk and not a painter. Little does he know that I spend at least two hours a day on my painting.”

“But Master, he says he never sees you there, so how do you explain these two hours a day?”

“Excellency, the figure of Judas must be of incomparable evil. Every day I search for this face in the criminal quarter, and every day I fail to find the evil that I am looking for. If I cannot find this man, however, I can use the head of the prior—it would do admirably, but I have hesitated for fear of hurting his feelings.”

Ludovico slapped his knees and roared with laughter. There were no more complaints.

Finally, in 1498, the scaffolding was removed from the painting and Leonardo’s masterpiece was revealed. The twelve apostles grouped at the table are shown each responding in his own way to the words of Christ, “One of you shall betray me.” Again hundreds flocked to see this latest marvel of Leonardo’s. Its striking influence was felt by generations of painters. Even now, more than four hundred and fifty years later, the world still comes to stand before the genius of Leonardo da Vinci in the refectory of Santa Maria delle Grazie.

The clouds of war were gathering again over Italy. In April of 1498, Charles VIII of France died and his successor was Louis of Orleans, who became Louis XII. The new King of France laid claim to the Dukedom of Milan, and Ludovico again tried to form an alliance against him. But the years of juggling enemy against enemy and friend against friend were now coming to an end. No one trusted Il Moro any more, and suddenly he realized that he was to be alone in this new fight. After nearly twenty years of power sustained by powerful alliances, Ludovico was forced to turn to his own people of Lombardy. Frantically he tried to correct the injustices of years. The people had been cruelly taxed to support the extravagances of the Sforza court, and, in addition, they had been badly treated by petty government officials. Ludovico now sought to repay the past miseries of his people and to rally them to his support. In such a spirit he remembered his court painter, Leonardo da Vinci, and gave him a vineyard and considerable piece of land not far from the Porta Vercellina.

Now, for the first time in his life, Leonardo knew financial security. With the income from the vineyard, and in the peace of his estate, he was left free to follow his own researches. He took no notice that his “peace” was surrounded by the threat of war. Indeed, he remained aloof from politics and court intrigues as much as was possible for a man living in the midst of such chaotic times.

Leonardo now had the opportunity to follow up an early interest—the study of plants. He made many beautiful drawings; no plant was too small to catch his eye. His notes on botany began to grow. With his genius for observation and analysis of nature, Leonardo made some extraordinary discoveries of botanical laws entirely unknown before his time. He wrote of the phenomenon of _heliotropism_, or the movement of plants toward or away from the sunlight. In addition, he described the phenomenon known as _geotropism_, or the growth of plants according to gravitational law, as for example, roots growing downward and shoots growing upward. He also defined the laws of phyllotaxis, which describe the system or order of leaf arrangement on a plant’s stem. That is, leaves are arranged spirally around a stem so that the third leaf above grows out over the third leaf below on one type of plant; or, on another type, the two third leaves are over the two third leaves below. The same natural laws apply to the branches of plants as well; they occur so that every leaf and branch can receive sufficient air and light. Amazingly enough, these laws, which Leonardo described so completely, were not rediscovered until almost two centuries later!

Leonardo went even further in his botanical studies. He experimented with gourds, planting them in various aqueous solutions; this anticipated modern methods of growing plants in chemicals. He also tested the actions of arsenic and mercury poisons in plants. He reproduced the shape and form of leaves by pressing them on paper coated with lampblack, a method that was not used again until the nineteenth century. Carefully noted, too, in his writings was the rising of sap from the roots to the branches by capillary action; this, too, was not rediscovered until much later—in the eighteenth century. Leonardo also extracted oils and essences from flowers and studied the influences of altitude on the development of vegetation. Indeed Leonardo’s very approaches to a systematic classification of plants were the forerunners of modern methods of classifying.

In the seclusion of his own home, as he continued his studies of geometry with Pacioli, Leonardo again turned to his observations of the heavens. On the roof of his house he had set up a small observatory for watching the sky at night. Often he looked at the stars through a pinhole in a sheet of paper. Leonardo did this to stop the “twinkling” of the stars which he recognized as an optical illusion. Moreover, by looking at the stars in this manner, he noticed that some were larger than others, and imagined to himself how our own earth might look from them. Would we not be but another “star” in a vast collection of stars? And if that were true—how could the earth be the center of the universe? By the same imaginary reasoning, he speculated on how we must look to someone on the moon. Realizing that the moonlight on earth faintly illuminates the dark side of the earth, he reasoned that then there must be an “earthlight” doing the same on the moon. Thus he was the first to explain the dim reflected light on the dark side of the moon. Moreover, Leonardo is known to have looked at the moon through a convex lens, and perhaps even a form of telescope. Indeed, he had built telescopic-type tubes with lenses in them and had written directions for their use. It seems certain that at about this time Leonardo became convinced of the heliocentric theory, the theory that states the sun is the center of our universe. On a sheet of mathematical notes Leonardo wrote in large letters, “the sun does not move.”

During this time he continued to seek out books on astronomy. Leonardo was familiar with Aristotle’s _Meteorology_, Archimedes’ _On the Center of Gravity_, and with _Problems in Aristotle’s Books of the Sky and the World_, a work by Albert of Saxony. This last book Leonardo had to read with the help of a Latin dictionary, because his Latin was not good. He had already read Plutarch, who had defined the moon as a solid. Plutarch had written further that the “spots” on the moon were the result of shadows cast by irregularities on its surface. This theory, that was apparently abandoned during the Middle Ages, supported the conclusions that Leonardo had reached by his own observations. But he still struggled against a mistaken idea of his own. For a long while he maintained that there were seas and waters upon the moon which accounted for the sunlight being reflected so brilliantly.

Meanwhile, in July of 1499, the French army had reached Lombardy. Ludovico was now in a state of desperation. He tried to appeal to the people of Milan, explaining that their heavy taxes had been due to the constant threats from abroad. But, however hard he tried to arouse their sense of loyalty to him, the public of Milan turned a deaf ear. They had not forgotten how Ludovico had allied himself with Charles VIII—a foreign king! Ludovico now had to put his trust in his army commander, Galeazzo da Sanseverino, despite warnings that this was a man of doubtful loyalty. Moreover, to make matters worse, Louis XII had succeeded in forming an alliance against Ludovico; and, among his allies was a powerful cardinal, son of Pope Alexander VI—the notorious Cesare Borgia.

From a note on a page of designs for supplying and heating a bath we know that Leonardo continued his quiet life, only vaguely disturbed by the political upheaval taking place around him. His note reads, “On the first day of August 1499 I wrote here of movement and weight.” He had made many experiments and calculations concerning the movement and weight of objects. He had drawn, for example, the flight of an arrow to describe motion through air and although he wrote no specific formula, he marked the three stages of its trajectory—the initial push, the slowing and the steeper downward path as the arrow’s momentum was overcome by the resistance of the air. He also defined the law of movement on an inclined plane and he arrived at the root principle of Newton’s law of gravitation when he wrote, “every weight tends to fall toward the center by the shortest way.”

A diagram of this period is probably the first scientific graph. Leonardo had experimented with two balls dropped from a height. First he dropped them together and then one after the other. In attempting to solve the mathematical problems presented by these falling bodies he drew a graph of vertical and horizontal lines. The times it took for the balls to fall were marked on the horizontal lines and the distances on the vertical lines—thus, he could trace their relationship.

But this peaceful time of productive work was running out for Leonardo. Ludovico’s commander, Galeazzo, had yielded the fortress of Alessandria to the French at the first battle. Ludovico himself had sent his sons and his treasure to his brother, Cardinal Ascanio, in Germany. When he saw that his cause was lost, he turned the Sforza castle over to Bernardino da Corte, a trusted commander, making certain that it was fully supplied with arms and food. Then in sorrow, Ludovico Sforza, Duke of Milan, left his city for the last time as ruler of Lombardy. The gates of Milan were opened to the French in October of 1499, and Bernardino da Corte surrendered the Sforza castle.

French soldiers now occupied Milan as conquerors and the people of the city were in a state of confusion. Those who could made their peace with the French; but others, who had been supporters of Ludovico, fled to avoid arrest. Leonardo, who would be suspect to the French, packed up his few possessions—although he did manage to retain his estate—and left, together with Pacioli and an apprentice, for Mantua.

9
_Cesare Borgia_

Leonardo, Pacioli, and Salai, the apprentice, arrived in Mantua in February of the year 1500. They were given refuge in the castle of Isabella d’Este, who was the sister of Beatrice, and the wife of Francesco Gonzaga, governor of Mantua. Isabella was one of the eminent women of her time and attracted to her court the intellectual life of Italy. In Leonardo she recognized the man of genius; indeed, she treated him as an equal, putting her castle at his disposal. She persuaded him to paint her portrait and Leonardo commenced a preparatory drawing.

In the evenings at the castle there were discussions and music and here Leonardo again met his pupil and companion on the trip from Florence so many years ago—Atalante Migliorotti who had left Milan in 1490 to assume the post of court musician to Isabella.

Although Leonardo had found a haven of peace in the political storm that raged about the city state of Mantua, he and Pacioli took to the road again for reasons unknown. Isabella d’Este, who still wanted Leonardo at her court, sent many a letter and messenger in the following years to bring Leonardo back—first to finish the portrait and then, when that failed, to sell to her any picture that Leonardo wished to send. Strangely enough, however, Leonardo seems to have turned his back upon the one sympathetic person he had met in a world of indifference.

The first, warm breezes of spring were blowing over the lagoons of Venice when Leonardo and Pacioli stepped ashore on the Piazzetta, or Little Square of San Marco. But the beauty of this jewel-like city rising from the sea was momentarily ignored by the two travelers for an angry, frightened crowd had gathered about the Doge’s palace on the Piazzetta.

The people of Venice were fearful because their fleet had just suffered a crushing defeat by the Turks. This meant that their power at sea, once supreme, was now no more. Year by year, moreover, their possessions in the east had been slowly whittled away, and now the city itself was threatened by invasion. At this same time, the Venetian ambassador, Manenti, hoping to make peace with the Turks, had been rudely rejected by them. Panic soon swept the city and rumors of the bloodthirsty infidel passed from person to person like the rush of an ugly wind. Barricades were put up and windows were barred. In this charged atmosphere, Leonardo and Pacioli sought out their lodgings.

Soon after Leonardo’s arrival here—either because his reputation had preceded him or, more likely, because of Fra Luca Pacioli’s recommendations—he became directly involved with the defenses of Venice. Immediately he was sent on an inspection trip of the city’s existing defenses, especially those inland from where an invasion would probably come. When he had seen them, he recommended a system of defenses along the Isonzo river near the present border of Yugoslavia, using the river itself to the disadvantage of the enemy. He also made suggestions for the improvement of forts, and even drew up plans for a completely new type—a circular fort. This consisted of a central, circular fort surrounded by two belts of fortresses each separated by a moat. In the outside moat were four semicircular outposts. Communication was by underground galleries. The total absence of superstructure and projecting balconies was a new idea for the times. Another new defense idea was to station in the moat itself a low, thick tower almost completely submerged, defended by a thin opening near the waterline. It was reached from the main fort by an underground passage and the gunsmoke was removed by vents. According to Leonardo no enemy could conceal himself in any part of the defenses and not be seen from such an outpost.

Leonardo’s most unusual scheme for defending Venice, however, was his idea of approaching an enemy fleet under the water and then putting holes in the hulls of their ships. Actually, the idea of diving was not a new one. Aristotle had written of diving and diving bells, and certainly the stories of pearl fishers in the Orient were well known in the Renaissance. But Leonardo designed a diver’s suit closely resembling those used today. This consisted of a complete suit of leather with helmet and eyepieces; it was made airtight by spirals of steel at the joints. He then added a bladder for holding air which fastened inside the suit at the diver’s chest. It is possible that Leonardo also invented an air chamber that could be used by the diver while under water—but he was very secretive about this invention for fear of how men might abuse such a discovery. He wrote, “... and this I do not publish or divulge, on account of the evil nature of man, who would practice assassinations at the bottom of the seas....”

Leonardo felt the same way about a “submarine” that he presented to the Councilors and Tribunal of Venice. This resembled a turtle’s shell with a raised bump on the center which was the “periscope.” When submerged the water probably rose to an area just around the “periscope,” but, again, the information about its air-supply is missing and the only reference to it is a reminder to close the “l—.” In addition, he invented a system of screws mounted in tongs with the borer in the middle for putting holes in the bottoms of enemy ships, and at the same time he thought of a defense against such an attack by designing the defending vessels with double hulls.

Among Leonardo’s other maritime devices were designs for boats that could dredge canals, harbors, and lagoons. What was the result of all these plans? We do not know. Whether any one of them was used against the Turks is a mystery.

At any rate, Leonardo and Pacioli left Venice that same spring and arrived in Florence in April of 1500. One of the purposes of Leonardo’s journey was to visit his father who was now living on Via Ghibellina with his fourth wife. Leonardo was now forty-eight. Still tall and straight with the strength of his youth, his face prematurely aged and his hair thinning back from his high forehead, Leonardo was more than ever an outstanding looking man. He still scorned fashionable clothes and dressed according to his own comfort which made him even more noticeable among the crowd. His deep-set eyes with their direct and penetrating glance, framed by his full, reddish beard, never missed a thing, although he now wore spectacles at his work.

Now that he was back in Florence, Leonardo needed lodgings and a job. He had banked his small savings, and he did not want to touch that. His father’s house with the five children of his present wife plus the sons from his previous marriages was too full to accommodate Leonardo. Moreover, the relationship between Piero and Leonardo was polite but distant, as Piero preferred the children of his later marriages.

Luckily, the place to live and the commission Leonardo needed presented themselves at the same time. The Church of the Annunciation of the Servite Order of Monks needed an altarpiece, and, as Leonardo’s fame was great, they offered him and his apprentice quarters in the monastery. Here, in the solitude of a monastic cell, Leonardo was able to return to his own researches. His long association with Fra Luca Pacioli continued as they worked together on Pacioli’s edition of Euclid’s _Elements_. At the same time, with his absorption in geometry, Leonardo commenced his studies of the transformation of solids; that is, changing the shape of something to another shape without diminishing or increasing its substance.

In his preoccupation with geometry, Leonardo had apparently done little about the commission which the Servite monks had given him. He finally yielded to their complaints, however, and commenced to draw the preliminary study for the subject, which was “St. Anne with the Virgin and Child.” Again his knowledge of geometry is most apparent in the finely constructed composition, every gesture of which is as plotted as a geometric exercise. In April of 1501, the drawing was finished; it caused an immediate sensation throughout Florence. For two days the public was allowed to pass in front of it.

But now a change was taking place in Leonardo. He was no longer content with simply painting. His highly original researches for pictures had slowly grown to the point where the research was more important than painting. In a sense the scientist had taken the brush from the artist. In two letters from Isabella d’Este’s emissary in Florence we learn, “He is entirely wrapped up in geometry and has no patience for painting.” This excerpt from a letter dated April 8, 1501, was followed six days later by another which said in part, “In brief, his mathematical experiments have made painting so distasteful to him that he cannot even bear to take up a brush.”

A few months after the completion of the St. Anne drawing, Leonardo received a letter signed by Cesare Borgia, Duke of Valentinois. Leonardo frowned and thought back to his last days in Milan. When King Louis XII of France had entered the city, he had summoned the painter of the “Last Supper” to an audience. The king had been generous in his praise and had tried to persuade Leonardo to remain. At that same audience had also been Cesare Borgia, an ally of the French. Leonardo remembered the man now—the dark hair and eyes, the black, arched eyebrows, and the face marked by some old disease. He was a powerful-chested, thin-hipped man who had originally been made a cardinal by his father, Pope Alexander VI. But the attractions of secular power soon persuaded him to abandon this title. With the enthusiastic help of his father, Borgia had fought, murdered, and deceived his way to a formidable position of authority in these last years. Leonardo, in the seclusion of the monastery, had lately heard that Borgia’s army had even been at the gates of Florence.

The letter addressed to Leonardo was an offer to assume the post of Architect and Military Engineer to His Excellency, Cesare Borgia. He thought of Ludovico Sforza—defeated and captured at the battle of Novara just a year ago as he attempted to regain his dukedom. Now the duke was a prisoner at Loches in Touraine; Leonardo had written of him, “The duke lost his State, his personal possessions and his liberty, and none of his enterprises have been completed.” And Leonardo also thought of his equestrian monument still standing in the castle being used for target practice by the French archers. Like the duke, nothing of his own had been completed either. Perhaps this Borgia offer was an opportunity. Leonardo decided to accept it.

In May of 1502, after having presented himself to Cesare Borgia in Rome, Leonardo began his hectic travels through Tuscany and Umbria. He was to inspect the fortresses and cities of Cesare’s new conquests there, and to make whatever recommendations he felt necessary for their improvements. Arriving in Piombino, he at once set down a project for draining the marshes and reclaiming the land. Also, while he was here, he spent hours by the sea watching the waves curl in from the Adriatic and studying the crash of water over the beaches. Moving on to Arrezzo, he drew up the first in a series of remarkable maps for the army of Vitellozzo which, with the backing of Cesare Borgia, was marching against Florence. These maps are bird’s-eye views of Tuscany and Umbria, and somewhat resemble modern aerial photographs. Drawn from Leonardo’s own observations, the green mountains stand, according to their height, in relief, with the roads winding over them and down through the valleys. The streams and their tributaries are in blue and even the villages and cities are drawn with great exactitude. Indeed Leonardo had learned his lessons from old Toscanelli well, and he was one of the first to bring the art of cartography to such perfection.

In July and August Leonardo was in Urbino and Pesaro, and by the 8th of August he had reached Rimini. Here he strengthened the fortifications and then rode quickly on to Cesena. Between Cesena, capital of the Romagna, and Porto Cesanatico, he spent from the middle of August to September planning a canal between the two, redesigning government buildings, and drawing up a new quarter to be built for the city of Cesena. At this time he constructed an instrument for telling him the speed of water currents in a stream. It told him whether the flow was swifter at the surface or at the bottom or on one side or the other of the stream’s bed.

In the meantime, Florence, alarmed at the growing power of Cesare Borgia, appealed to Charles d’Amboise, Regent of Milan for France, to come to her aid. Charles responded in the absence of the French King and helped to protect Florence. The enemies of Cesare took advantage of this to form an alliance, and soon Cesare was being forced back from his newly won possessions. Cesare himself then hastened to Milan, and there he suddenly came face to face again with Louis, the King of France, who was on his way to Naples. Borgia, who could exert great charm and influence when he wished, persuaded the king that, all rumors to the contrary, he, Cesare, was fighting the enemies of France. Again he won over the French, which greatly strengthened his position. Then, from Pavia, he issued a decree placing every facility possible at Leonardo’s disposal. In addition, he instructed all officials to help Leonardo in every matter, referring to him as “our highly esteemed court architect.”

While Leonardo was in Porto Cesanatico, a delegation from Bayzid II, Sultan of Turkey, paid a visit to Cesare Borgia. Among other things the delegation was looking for an engineer to build a bridge between Constantinople and Pera to replace a temporary wooden structure. Leonardo designed for them a single-arched bridge with double ramps at either end (looking very much like a present-day “thruway” entrance). He provided that it should be approximately twelve hundred feet long, eighty feet wide, and one hundred and forty feet above the water.

In his travels through the countryside, Leonardo could not help but notice how primitive the mills were. Feeling how strongly the wind blew in from the sea, he designed a windmill with a roof that turned with the sails. For the mechanism inside he devised a band brake—a semicircle of wood into which the large cogwheel of the mill was forced. This mill resembles the “Dutch” mills of the Netherlands and was among the first of its type to be brought into existence.

In the fall Leonardo was at Imola. There he created another of his beautifully rendered maps. He drew this with the help of a magnetic compass of his own invention. It consisted of a board with an arc on it and a compass needle, and was probably the first magnetic needle on a horizontal axis. This time the map was of the city itself, the walls, the castle and the principal buildings all touched with color and the river winding through the fields. Drawn in the shape of a circle, it resembles a view through a telescope from directly above. In Imola, too, he met Niccolò Machiavelli, the famous historian and political scientist, who was an emissary from the Signoria, the Council which now governed Florence. These two men became friends and, later, collaborators in Leonardo’s scheme to make the Arno river navigable to the sea.

At this time Cesare Borgia, having achieved great success in his military campaigns and confident of his conquests, decided to return to Rome. With the disbanding of Borgia’s headquarters at Imola, Leonardo’s duties were finished. Together with his new friend Niccolò Machiavelli and two other Florentines, he left Imola and the service of Cesare Borgia to return to Florence.

In January of 1503, a mathematician named Giovanni Battista Danti attempted a flight in a machine that he had designed. This flight was part of the entertainment at a wedding reception in Perugia. Danti climbed into his apparatus on top of the tower of St. Mary of the Virgin. It was pushed off into the air, hovered a few seconds, then began slowly drifting toward the ground. But suddenly, one of its wings hit a building projection and it crashed. Danti was carried away with a broken leg.

The news of the event traveled quickly to Florence.

When Leonardo heard about it, he eagerly questioned all those who had either seen it or had heard it described first hand. Danti’s attempted flight excited Leonardo for now he realized that he was no longer alone in his search. With a sense of urgency he returned to the problems of flying. He felt now that the solution to flight might be in the swift gusts of air through the ravines and the spread wings of the eagle drifting high in the sky.

10
_Shattered Hopes_

Before Leonardo could return to the problem of flight, however, he was again faced with the necessity of supporting himself and his growing household. The small fees he received for taking on apprentices hardly covered the cost of housing and feeding them. Moreover, the equipment he had to buy for his scientific researches added further to his strained budget. So, when a servant from Francesco del Giocondo, a rich Florentine merchant, presented himself at the gate with the request that Leonardo accept a commission to paint Francesco’s wife, Leonardo was only too glad to accept. The name of Francesco’s wife was Madonna Lisa, or Mona Lisa for short. Leonardo painted her portrait on and off for the next three years. Thus, what started as a minor commission ended as the one painting—in addition to the “Last Supper”—that most people today associate with the name of Leonardo da Vinci.

Having secured this work, Leonardo turned back to his studies of birds in flight and the nature of air. The soaring wings of eagles and hawks and the way they rode the currents with hardly a dip of their spread wings guided Leonardo’s thinking from pure mechanics to machines that act more on the principle of the glider. He proposed to write a treatise on the nature of birds’ flight, and, with his usual thoroughness, he began to weigh, dissect, and reconstruct various types of birds and their wing structure. He realized that one of the main difficulties of gliding was maintaining balance, or, more accurately, maintaining the center of gravity. From previous observations Leonardo had noted that man is capable of making the same motions that a bird does. He had also measured the strength of a man’s legs and had calculated that man has twice the power in his leg muscles that he needs for standing. Consequently he began to redesign his machine making use of man’s arms and legs to operate or “flap” the wings instead of standing him on a platform.

The first of Leonardo’s new designs was a sort of harness apparatus strapped across the shoulders of the flyer who was supposed to be able to keep himself balanced by moving the lower part of his body. He could manipulate the flight by handles that were connected to the flexible, outer parts of the wings. These wings were designed from the webbed wings of the bat. Surprisingly enough, this device closely resembled the experimental gliders used by Otto Lilienthal almost four centuries later in Germany.

Leonardo was now approaching other solutions to pure flight when further hostilities interrupted his work. Florence and Pisa were in bitter rivalry, and their struggle had assumed the proportions of a major war. The Florentine army was now practically at the gates of Pisa. Niccolò Machiavelli urged the Signoria to enlist the help of Leonardo da Vinci, who might be able to think of an immediate plan for destroying Pisa and her army. Never one to think in terms of an immediate battle or a temporary success, Leonardo put forth a daring and sweeping plan that would forever reduce the power of Pisa. The plan was as simple as it was monumental—divert the Arno river from its course into two canals that would empty into the sea at Leghorn south of Pisa. In this way, Pisa would lose her water supply and her opening to the sea.

The plan met with immediate approval and by the end of July 1503, Leonardo was sent out to survey the entire course of the river. He was accompanied by Giovanni “the Piper,” a man who was frequently employed on minor engineering projects and who was the official player of the pipes to the city of Florence. Giovanni was also the father of Benvenuto Cellini, who became the most famous goldsmith of the Renaissance. As they made their way to Pisa, Leonardo made some more of his extraordinary maps of the area, paying particular attention to the course of the Arno and its tributaries. These maps later inspired him to plan a whole series showing the main watersheds of Italy.

When he rode into the Florentine camp drawn up before Pisa, Leonardo designed from his observations and maps, a dam on the Arno to regulate the course of the river. This bird’s-eye view map is a marvel of exactness. It shows the flow of the river hitting the dam with its swirling backwash and overflow. Leonardo’s knowledge of the movement of water was so great and his craftsmanship in drawing so fine that the water in this map seems to flow before one’s eyes. One of the main problems in regulating the Arno was its tendency to continually be shifting its bed by the deposits of new sediment, and Leonardo realized it would be a long time before this project could be completed.

When he returned to Florence he presented to the Signoria, as part of his survey, various machines to hasten the excavation of the Arno. He had designed a crane that would assist in the digging out of two different levels at the same time. He also submitted the results of his calculations on the saving of muscular energy by the use of such machines. In addition, Leonardo proposed to use the water in the canals for irrigation purposes and had even calculated what the volume and velocity of a jet of water would be if projected from an opening in the bottom of the canal wall into an irrigation ditch. As if this were not enough, he had invented a practical method of piling as a foundation for the lock-basins to protect them against the dangers of erosion.

A separate map of this period on the flow of rivers in general was intended to relate to his treatise on the nature of water. In this treatise is the first outline of the fundamental principles of hydrodynamics, as for example:

The velocity of a current increases with the slope and decreases with the winding of the riverbed.

The volume of a river is in proportion to the width of its bed, the slope and the depth of the water being equal.

The slope and width being equal, the speed of the current is greatest in the deepest part of the river.

The excavation force increases at the narrowest section of the river.

Because of the grumbling of the military commanders at what they considered a waste of time, Machiavelli had to intervene with the Signoria before Leonardo was sent out again with documents of authority to continue with his plans. He spent well into the fall surveying the Arno and in October he was back in Florence.

Meanwhile the fighting between Pisa and Florence had been lessened by two political changes. In August Pope Alexander VI had died and his son Cesare Borgia became seriously ill. The Republic of Florence was now free of its most dangerous enemies—the Borgias. The city relaxed in its new security and the hostilities between Florence and Pisa died down to an uneasy armed watch.

Leonardo quickly took advantage of the situation to present an early dream of his to the Signoria. He again put forth his idea of a commercial canal to the sea and made mention of the great advantages there would be for all the mills, lumber yards, forges and other commercial interests in utilizing the water power that would be available from his project. Piero Soderini, the governor of the city-state of Florence, was impressed and thought of the glory it would bring to Florence and himself. He told Leonardo he would present it to the Signoria.

Leonardo now plunged into a winter of great activity. Forced to draw from his savings, he had rejoined the guild of painters in October of 1503, and then applied for the commission of painting the murals in the council chamber of the Palace of the Signoria. It had been planned to decorate this great hall with scenes commemorating famous Florentine victories, and Leonardo chose the battle of Anghiari where the soldiers of Florence defeated the Milanese in 1440. In addition to working on the “Mona Lisa” and continuing with the canal project—for which he was now designing great suction pumps to lift rivers from one level to another—he turned again to astronomy and geology.

Leonardo, while investigating the course of the upper Arno, had come across much evidence that the land there had at one time been completely under water. Various types of ancient ocean life and vegetation lay scattered in layers along the ridges of the mountains, and these Leonardo collected and brought back to his studio. He wrote, “above the plains of Italy where now birds fly in flocks, fishes were wont to wander in large shoals.” He reread Ptolemy, the ancient Greek geographer Strabo, and even Sir John Mandeville, an English author of travel books, in his quest for knowledge of distant places. He talked to travelers, sailors, and wrote to friends to send him information about the countries they had seen or lived in. Strabo, in particular, had set forth the doctrine that the earth’s transformation had taken place by the forces of volcanoes and water, but the wisdom of these early men had been obscured by the closed minds of the Middle Ages.

Even in his own time of reawakening knowledge—the Renaissance—Leonardo had to contend with the combined superstition of the Church and the ignorance of misguided scholars. For example, the Church believed in the great flood, as described in the Bible, and the scholars claimed that if what Leonardo said were true—that the earth was the result of an evolutionary process—there would have been written records. To this latter Leonardo responded, “... sufficient for us is the testimony of things produced in the salt waters and now found again in the high mountains far from the seas.” But Leonardo’s conception of the evolution of the earth was mistaken in one respect. He regarded the earth as organic—living—and the flow of water he believed to be like the flow of blood in man. Indeed, according to Leonardo, all living creatures were reflections of a living, breathing earth. It was only when he again turned his eyes inquiringly toward the moon and the laws of the universe that he began to realize his error.

It had been the idea that the earth was the center of the universe which supported Leonardo’s theory of an organic earth. Yet after years of observation and study he abandoned this theory and, with the eye of a man centuries ahead of his time, he wrote in his notes, “The moon has every month a winter and a summer. And it has greater colds and greater heats and its equinoxes are colder than ours.” He went further and identified the elements existing on the moon such as “water, air, and fire,” and described them and their functions as being like those on our own earth. In so doing he recognized the existence of the moon as a solid in space, reflecting the light of the sun—one of many “stars” in a universe. With his acceptance of this concept he realized that the earth could not be organic.

In May of 1504, the Signoria complained to Leonardo that there had been no progress on the proposed paintings for their council chamber, even though he had already been partially paid for them. Accordingly, he was forced to sign a document that he must be finished by February of next year or refund all monies paid him. As was his custom he had made many preliminary drawings. Although he was well acquainted with horses he had again researched their anatomy and actions. Pages of rearing, frightened horses and men in combat covered his studio tables. On one of these pages there are sketches of the heads of a lion, some horses and a man—all with fierce expressions on their faces. Here Leonardo hinted at the comparative anatomy of expression in man and animal that Darwin was to write about almost four hundred years later.

But the paintings could wait, for now the Arno River was in spring flood. The time had arrived to make the first attempts at diverting the river into its new course. Leonardo was again in the field supervising the work. There had been much opposition to Leonardo’s canal from both the army captains and the Signoria. It was called a whim and a crazy idea, but Piero Soderini and Niccolò Machiavelli were stubborn in their defense of Leonardo’s plan and they overcame all opposition to it. And indeed, the raising of the sluice gates was successful and the Arno actually flowed into its new bed. The tensions in the camp and in the Council of Florence were eased. The only sad person was Leonardo, for he had just learned of the death of his father.

Leonardo felt the loss deeply. Outwardly, however, he only acknowledged the death of his father at a distance. Not only had Leonardo and his father drifted apart over the years, Piero left nothing to Leonardo in his will. His father’s other children quarreled among themselves over what money he did leave. Leonardo’s one friend in the family was Uncle Francesco, who was still living in Vinci. When he heard of his brother’s will, Francesco made out a will of his own and left everything to the nephew he loved—Leonardo.

After having successfully diverted the Arno river, it was now necessary for Leonardo to return to the painting commissioned by the Signoria for its council chamber. But recently, Leonardo had suffered a rebuff in this work. Originally he had been given the whole room to do but now the opposite wall had been assigned to another man—Michelangelo Buonarroti. Leonardo had first met the young Michelangelo when he helped to judge the best location for Michelangelo’s monumental statue of David. The two men were opposites in every way. Leonardo, fifty-two years old, carefully dressed, cool and detached, was a man whose every action was the result of a thoughtful and analytical mind. Michelangelo, twenty-six years old, his clothes rumpled and covered with marble dust, was passionate and moody—an impulsive youth totally dedicated to art. They did not like each other, and now Leonardo was forced into a rivalry for which he had no heart.

The duel between these two giants of art aroused the whole of Florence and there was a constant stream of people watching them at work. Michelangelo was given a studio in the hospital of Sant’ Onofrio and Leonardo was working in the Papal Chamber in Santa Maria Novella. Among the many people who came to watch Leonardo was a young man of nineteen. He was already a pupil of Perugino and the experience of meeting and learning from Leonardo was to influence him the rest of his life. His name was Raffaello Sanzio—one of the great Renaissance painters of Italy and known to us by the name of Raphael.

While Leonardo worked at Santa Maria Novella he had the opportunity of continuing his studies in anatomy. Dissections at that time were novelties and when one was performed the doors were thrown open to the public. Leonardo must have attended the public dissections at the Church of Santa Croce. Now at Santa Maria Novella there was a hospital, and here Leonardo was able to continue his own dissections without interruption. In a cool room below the hospital where bodies were kept Leonardo worked late into the night. By the flickering lights of candles and in the silence of the world about him he studied, drew, and wrote in his notes of the wonders of the human body.

He performed autopsies on people who had died natural deaths—a special permission granted to him by the monks of the church, and among these autopsies are the first written reports of some of the diseases that are the causes of death. Arteriosclerosis, or stony growths in the blood vessels, and pulmonary tuberculosis, a nut-like growth in the lung, are among the discoveries Leonardo made in his lonely searches, although he did not use these medical names for them.

Above all Leonardo was attracted to the function of the muscles, especially those in the arms and legs. So faithfully, in fact, did he record the origin and insertion of all the various muscles that these drawings can be used as anatomical models today. Moreover, he believed that a good drawing was worth pages of words describing human anatomy. The muscles were rendered as cords so as to better understand their function. He described this function as one of pulling instead of pushing and he noted that for every muscle there is an opposing muscle. When one contracts the other expands. For example, when you tighten the biceps in your arm you can feel the looseness of the triceps, the muscle on the opposite side.

As the end of the summer of 1504 approached, Leonardo’s dream of the canal from Florence to the sea was destroyed. The summer had been hot and without rain. The water in the canal dried up and the Arno river returned to its original course. All the old arguments against the plan were revived. The Florentine army captains rebelled against the job of defending a useless project. Again Soderini and Machiavelli intervened. After heated debates in the Council of Eighty, which had been called into special session, Machiavelli himself was sent out to oversee the work. It was brought almost to completion when in late October disaster struck. The rains that had failed to come in summer fell from the heavens in great cloudbursts. Storm after storm swept the valleys. The workmen left and the soldiers were recalled. The Pisan army rushed in to fill up the diggings and one final storm washed away the dream to nothing but eroded mounds of dirt.

Leonardo buried his disappointment in other work. When the drawing for the Battle of Anghiari was ready for transfer to the wall of the council chamber, he had a special scaffolding made of his own invention which worked on the principle of a pair of scissors standing on end, with a long platform on top. As the legs were spread the scaffolding was lowered and when they were pinched together it was raised. The wall had been prepared with a special mixture which he hoped would bring out the brilliance of his tempera colors. With several assistants who had been assigned to him by the Signoria the violence of the Battle of Anghiari was transferred to the wall and the actual painting was begun.

During the winter months Leonardo would relax from his work on the huge painting and his dissections to roam the country around Florence. He visited the slaughterhouses where the animals were killed and prepared for market. Here he was able to examine the hearts of animals just slaughtered and to note that the heart retained its action until the body was almost cold. He made a glass model of the aorta (the main artery leading from the heart) of an ox with which he could experiment on the flow of the blood. He intended to add to it a glass tube for one of the semilunar valves of the heart. He also experimented with a frog, dissecting its brain, heart, and entrails and noted that it ceased to twitch only when the spinal cord was severed. In his notes, he wrote, “The frog instantly dies when the spinal cord is pierced; and previous to this it lived without head, without heart or any bowels or intestines or skin; and here therefore it would seem lies the foundation of movement and life.” He was of course searching for the reasons that muscles moved and from where the impulses originated.

One of Leonardo’s favorite places to visit was Fiesole where his uncle Allessandro Amadori lived. Uncle Allessandro was the brother of Leonardo’s first stepmother and, since he had loved her so much, he likewise felt an affection for Allessandro. At Fiesole, which rises over Florence in a steep ascent, Leonardo could watch the birds circling in the air below him.

On these lofty heights, he would unfold his drawings of flying machines. Leonardo had progressed now to a point where an actual flight was all that was left. He had designed a sort of flying boat—a shell with wings that moved up and down and he had introduced a tail like that of a bird. He had noted that the tail of a bird acts as a rudder, a stabilizer and a brake when landing.

But Leonardo’s most recent design was one that was called an _ornithopter_. It consisted of a wooden frame, two huge wings like a bat’s, a series of ropes and pulleys and a windlass, all planned with the lightest of materials. The flyer, lying prone in the frame, his feet in leather stirrups connected to the wings by pulleys, would move his feet up and down to flap the wings while, at the same time, he operated the windlass with his arms in order to guide the machine. Soon he hoped to build this machine and try it out.

Meanwhile, Leonardo returned to his painting in the council chamber with impatience, for spring was approaching and the time to finally realize his dream of flying would be at hand. Aside from an assistant who had tested the pedals and windlass, no one knew of his plan to actually put his machine in the air.

Weeks passed and the painting was almost finished. The huge wall was covered with plunging horses and embattled soldiers. The colors were brilliant on the special mixture he had prepared for the wall—but they were not drying as they should have. Something was wrong. To speed the drying process, Leonardo had a special fire built in the room that directed the heat onto the painting. Spectators were allowed to watch as the waves of hot air rose against the wall. Then—disaster began slowly with a small trickle of paint from the top! Before anybody could put out the fire, the great figures and horses slowly melted down the wall in shiny, sticky streaks of color. Leonardo fled the room in an agony of shame.

With his own friends discouraged, the Signoria hostile, and the friends of Michelangelo triumphant, Leonardo went back to Fiesole. He went back with his secret dream of flight. The world would soon forget the Battle of Anghiari—but the conquest of the air, if he could achieve it, would live forever.

In the spring of 1506, from the slopes of Monte Cecero near Fiesole, legend tells us that a great bird sailed into the air and disappeared. No one knows whether Leonardo actually flew his machine or not but Girolamo Cardano, the son of a friend of Leonardo, wrote, long after Leonardo had died, “Leonardo da Vinci also attempted to fly, but he failed. He was a fine painter.” Another dream had been shattered.

11
_The Return to Milan_

Leonardo felt his fifty-four years that spring day in 1506. The bitterness of his failures and the frustration of his dreams added considerably to the weight of his years. All morning he had wasted in argument with Soderini and the Signoria. If it had not been for the letter from Charles d’Amboise, Viceroy of the King of France for Milan, he would have felt like a beggar. Charles d’Amboise had been appointed military governor of Milan by Louis XII ever since the French had conquered that city and captured Duke Ludovico Sforza. But the authority of the letter had finally won a grudging consent from Soderini. Leonardo looked about him to see if he had forgotten anything and slowly climbed onto his horse. He nodded to Salai, his apprentice, looked back to see if his servant had the pack-horses ready, and started down the street leading the small procession. He was going back to Milan.

Leonardo took out the letter and reread it. The words were respectful and admiring—and in French. They requested the presence of “Maître Leonard de Vinci” at the court of Charles d’Amboise, for purposes of painting and other “diverse projects” for the King of France. The letter restored a measure of confidence to Leonardo’s self-respect. Before Leonardo left, Soderini had made him sign a letter in which Leonardo promised to return to Florence within three months and to leave a deposit of one hundred and fifty florins which would be held against his return. It was signed, notarized and dated May 30, 1506. Nevertheless, Leonardo had decided to accept the French envoy’s offer; moreover, he looked forward to the prospect of returning to his vineyard at Porta Vercellina and the understanding of a sympathetic patron.

Indeed, Charles d’Amboise turned out to be more than sympathetic. He recognized Leonardo as a great artist; but even more, he was one of the few patrons who could appreciate the magnitude of Leonardo’s scientific and mechanical genius. In the court of Charles, Leonardo once more enjoyed a time of peace and an assured income. The French Vice-Chancellor of Milan, Geffroy Carles, who was second in command, was also a distinguished scholar and a patron of the arts and natural sciences. With the admiration and support of these two men and especially with the distant backing of King Louis XII of France, Leonardo’s dismal memories of Florence began to fade.