With the work of the individual artists we shall become better acquainted in subsequent chapters. Here we can merely name their leaders. In architecture and sculpture respectively, Filippo Brunelleschi (1377-1446) and Donatello (1386-1466) are the ruling spirits of the age. Their mutual friendship and brotherly rivalry almost recall the loves of Dante and Cavalcanti in an earlier day. Although Lorenzo Ghiberti (1378-1455) justly won the competition for the second gates of the Baptistery, it is now thought that Filippo ran his successful rival much more closely than the critics of an earlier day supposed. Mr Perkins remarks that "indirectly Brunelleschi was the master of all the great painters and sculptors of his time, for he taught them how to apply science to art, and so far both Ghiberti and Donatello were his pupils, but the last was almost literally so, since the great architect was not only his friend, but also his counsellor and guide." Contemporaneous with these three _spiriti magni_ in their earlier works, and even to some extent anticipating them, is Nanni di Banco (died in 1421), a most excellent master, both in large monumental statues and in bas-reliefs, whose works are to be seen and loved outside and inside the Duomo, and in the niches round San Michele in Orto. A pleasant friendship united him with Donatello, although to regard him as that supreme master's pupil and follower, as Vasari does, is an anachronism. To this same earlier portion of the Quattrocento belong Leo Battista Alberti (1405-1472), a rare genius, but a wandering stone who, as an architect, accomplished comparatively little; Michelozzo Michelozzi (1396-1472), who worked as a sculptor with Ghiberti and Donatello, but is best known as the favoured architect of the Medici, for whom he built the palace so often mentioned in these pages, and now known as the Palazzo Riccardi, and the convent of San Marco; and Luca della Robbia (1399-1482), that beloved master of marble music, whose enamelled terra-cotta Madonnas are a perpetual fund of the purest delight. To Michelozzo and Luca in collaboration we owe the bronze gates of the Duomo sacristy, a work only inferior to Ghiberti's "Gates of Paradise."