Hydraulics and the Science of Politics And I compare [fortune] to one of those ruinous rivers that, when they become enraged, flood the plains, tear down trees and buildings, taking up earth from one spot and placing it upon another; everyone flees from them, everyone yields to their onslaught, unable to oppose them in any way. But although they are of such a nature, it does not follow that when the weather is calm we cannot take precautions with embankments and dikes, so that when they rise up again either the waters will be channeled off or their impetus will not be either so unchecked or so damaging.*

Portrait of Niccolò Machiavelli

by Santi di Tito (1536-1603)

Portrait of Leonardo da Vinci

Attributed to followers of Leonardo In addition to figuring in the political theory of The Prince, rivers had a part to play in real life politics for Machiavelli. In the early years of the sixteenth century, Machiavelli joined together with Leonardo da Vinci in a massive effort to divert the Arno river as part of the war effort against the nearby city of Pisa. In 1503 the Florentine republic was in dire straits, threatened from within and without. Within, pro-Medici supporters worked to undermine the republican government that Machiavelli served. Outside of its walls, Florence faced the growing threat of Cesare Borgia, who had the support of the French king, Louis XII. To its west, Florence was at war with the city of Pisa. Both cities sought to control the Arno river, and Pisa could easily cut Florence off from the sea. For a republican government, the political instability that would accompany such an economic disaster could spell its doom. Leonardo da Vinci was as much engineer, scientist and inventor as he was artist. Many of his drawings are devoted to investigations in optics, topography, and dynamics, and much of his career was spent designing military weapons, architecture and vehicles and working on civil and hydraulic engineering projects.

Leonardo da Vinci

Possible canal routes for diverting the Arno River In 1503 Leonardo da Vinci and Machiavelli began work on a project that they believed would end the threat from Pisa forever. They proposed to divert the Arno river away from Pisa, leaving the city literally high and dry and making Florence a seaport. The beleaguered Florentine republic approved funds for the project. Leonardo spent the spring and summer drawing a series of stunning "bird's eye" maps of the Arno river and the surrounding landscape. In August 1504, the project began. It was a huge undertaking that posed critical problems for earth removal and directing water flow. Time was of the essence, both for financial and military reasons. The engineer in charge of the project was forced to make cost-cutting measures. Leonardo devised a digging machine to expedite matters and save on labor, but apparently it was never built. Map of Imola

by Leonardo de Vinci In October 1502 Leonardo spent several weeks in Imola with Cesare Borgia, who commissioned him to map the city and study the fortress with possible modifications in mind.

Leonardo da Vinci

Digging Machine The result was failure. The diversionary ditches were too shallow and the river did not follow the new course. Efforts to deepen the ditches began, but a storm destroyed the earthworks. What nature left, the Pisans demolished. According to Roger Masters, who has written a history of the project, "the Arno diversion could be called a magnificent failure. Niccolò and Leonardo tried to control the flow of history and the flow of the river by combining science, technology, and political power. The ambition to use this means to conquer nature, common place today, had never been attempted in quite this way on such a scale."** The Florentine republic struggled on for a few more years. In 1512, the Spanish army defeated Florence, and Guiliano de Medici siezed power: a most unfortunate turn of events for Machiavelli. In his exile, he turned his attention from the science of engineering to the science of politics with the writing of The Prince. * Niccol ò Machiavelli, The Prince, trans. by Peter Bondanella and Mark Musa, 1989, p.82. ** Roger D. Masters, Fortune is a River: Leonardo da Vinci and Niccolò Machiavelli's Magnificent Dream to Change the Course of Florentine History (1999), 133. Masters' account of the project can be found on pages 81-133. In 1434, another artist, Brunelleschi, had proposed that Florence divert a river and thereby flood the city of Lucca. This, too, had failed.