III.

Years in Milan

In about 1482 Leonardo entered the service of Ludovico Sforza, Duke of Milan, having written the duke an astonishing letter in which he stated that he could build portable bridges; that he knew the techniques of constructing bombardments and of making cannons; that he could build ships as well as armoured vehicles, catapults, and other war machines; and that he could execute sculpture in marble, bronze, and clay. He served as principal engineer in the duke’s numerous military enterprises and was also active as an architect. In addition, he assisted the Italian mathematician Luca Pacioli in the celebrated work Divina Proportione (1509), a treatise on aesthetics centring on the concept of the Golden Section.

Evidence indicates that Leonardo had apprentices and pupils in Milan, for whom he probably wrote the various texts later compiled as Treatise on Painting (1651; trans. 1956). The most important of his own paintings during the early Milan period was The Virgin of the Rocks, two versions of which exist (1483-1485, Louvre, Paris; 1490s to 1506-1508, National Gallery, London); he worked on the compositions for a long time, as was his custom, seemingly unwilling to finish what he had begun. From 1495 to 1497 Leonardo laboured on his masterpiece, The Last Supper, a mural in the refectory of the monastery of Santa Maria delle Grazie, Milan. Unfortunately, his experimental use of oil on dry plaster (on what was the thin outer wall of a space designed for serving food) led to technical problems, and by 1500 the mural had begun to deteriorate. Since 1726 attempts have been made, unsuccessfully, to restore it; a concerted conservation and restoration programme, making use of the latest technology, was begun in 1977 (completed in 1999) and has reversed some of the damage. Although much of the original surface is gone, the majesty of the composition and the penetrating characterization of the figures give a fleeting vision of its vanished splendour.

During his long stay in Milan, Leonardo also produced other paintings and drawings (most of which are now lost), theatre designs, architectural drawings, and models for the dome of Milan Cathedral. His largest commission was for a colossal bronze equestrian statue of Francesco Sforza, father of Ludovico, for the courtyard of Castello Sforzesco. In December 1499, however, the Sforza family was driven from Milan by French forces. Leonardo had made the clay model but contingency dictated that the metal intended for the statue be used for cannon instead. The model was destroyed by French archers, who used it as a target. Leonardo returned to Florence in 1500.