Leonardo da Vinci, Pathfinder of Science

by Henry S. Gillette

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.