The first great apostle of the new sculpture was Lorenzo Ghiberti (1378-1455), whose marvelous doors on the baptistery at Florence elicited the comment of Michelangelo that they were "worthy of being placed at the entrance of paradise." Slightly younger than Ghiberti was Donatello (1383-1466), who, among other triumphs, fashioned the realistic statue of St. Mark in Venice. Luca della Robbia (1400-1482), with a classic purity of style and simplicity of expression, founded a whole dynasty of sculptors in glazed terra-cotta. Elaborate tomb- monuments, the construction of which started in the fifteenth century, reached their highest magnificence in the gorgeous sixteenth-century tomb of Giovanni Galeazzo Visconti, the founder of the princely family of Visconti in Milan. Michelangelo himself was as famous for his sculpture as for his painting or his architecture; the heroic head of his David at Florence is a work of unrivaled dignity. As the style of classic sculpture became very popular in the sixteenth century, the subjects were increasingly borrowed from pagan literature. Monuments were erected to illustrious men of ancient Rome, and Greek mythology was once more carved in stone. The extension of the new sculpture beyond Italy was even more rapid than the spread of the new architecture. Henry VII invited Italian sculptors to England; Louis XII patronized the great Leonardo da Vinci, and Francis I brought him to France. The tomb of Ferdinand and Isabella in Spain was fashioned in classic form. The new sculpture was famous in Germany before Luther; in fact, it was to be found everywhere in sixteenth-century Europe. [Sidenote: Painting] Painting accompanied sculpture. Prior to the sixteenth century, most of the pictures were painted directly upon the plaster walls of churches or of sumptuous dwellings and were called frescoes, although a few were executed on wooden panels. In the sixteenth century, however, easel paintings--that is, detached pictures on canvas, wood, or other material--became common. The progress in painting was not so much an imitation of classical models as was the case with sculpture and architecture, for the reason that painting, being one of the most perishable of the arts, had preserved few of its ancient Greek or Roman examples. But the artists who were interested in architecture and sculpture were likewise naturally interested in painting; and painting, bound by fewer antique traditions, reached a higher degree of perfection in the sixteenth century than did any of its allied arts. Modern painting was born in Italy. In Italy it found its four great masters--Leonardo da Vinci, Michelangelo, Raphael, and Titian. The first two acquired as great a fame in architecture and in sculpture as in painting; the last two were primarily painters.