Life
Leonardo was born on April 15, 1452, in the small Tuscan town of Vinci, near Florence. He was the son of a wealthy Florentine notary and a peasant woman. In the mid-1460s the family settled in Florence, where Leonardo was given the best education that Florence, the intellectual and artistic center of Italy, could offer. He rapidly advanced socially and intellectually. He was handsome, persuasive in conversation, and a fine musician and improviser. About 1466 he was apprenticed as a garzone (studio boy) to Andrea del Verrocchio, the leading Florentine painter and sculptor of his day. In Verrocchio's workshop Leonardo was introduced to many activities, from the painting of altarpieces and panel pictures to the creation of large sculptural projects in marble and bronze. In 1472 he was entered in the painter's guild of Florence, and in 1476 he is still mentioned as Verrocchio's assistant. In Verrocchio's Baptism of Christ (circa 1470, Uffizi, Florence), the kneeling angel at the left of the painting is by Leonardo.

In 1478 Leonardo became an independent master. His first commission, to paint an altarpiece for the chapel of the Palazzo Vecchio, the Florentine town hall, was never executed. His first large painting, The Adoration of the Magi (begun 1481, Uffizi), left unfinished, was ordered in 1481 for the Monastery of San Donato a Scopeto, Florence. Other works ascribed to his youth are the so-called Benois Madonna (c. 1478, Hermitage, Saint Petersburg), the portrait Ginerva de' Benci (c. 1474, National Gallery, Washington, D.C.), and the unfinished Saint Jerome (c. 1481, Pinacoteca, Vatican).

About 1482 Leonardo entered the service of the duke of Milan, Ludovico Sforza, 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 armored 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 active also as an architect. In addition, he assisted the Italian mathematician Luca Pacioli in the celebrated work Divina Proportione (1509).

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 (1483-85, Louvre, Paris; 1490s to 1506-08, 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 labored 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) was technically unsound, and by 1500 its deterioration had begun. Since 1726 attempts have been made, unsuccessfully, to restore it; a concerted restoration and conservation program, making use of the latest technology, was begun in 1977 and is reversing 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 splendor. During his long stay in Milan, Leonardo also produced other paintings and drawings (most of which have been lost), theater designs, architectural drawings, and models for the dome of Milan Cathedral. His largest commission was for a colossal bronze monument to Francesco Sforza, father of Ludovico, in the courtyard of Castello Sforzesco. In December 1499, however, the Sforza family was driven from Milan by French forces; Leonardo left the statue unfinished (it was destroyed by French archers, who used it as a target) and he returned to Florence in 1500.