ED GLAESER: I’m here in the Harvard Art Museum in front of an exquisitely beautiful Virgin and Child, painted by Sandro Botticelli, the legendary Florentine painter. Botticelli was part of a chain of artistic genius that flourished in Renaissance Florence. It starts when Brunelleschi figures out the basic mathematics of linear perspective, how to make two-dimensional surfaces appear three-dimensional. He passes that wisdom along to his friend Donatello, who puts it on the wall of Orsanmichele in low relief sculpture. Donatello passes along to Masaccio, who paints the Brancacci Chapel. Marvelous painting of Saint Peter finding a silver coin in the belly of a fish. According to Varsari, Fra Filippo Lippi, that less than saintly monk, learns his craft by sitting at the feet of Masaccio. Lippi was the teacher of Botticelli, and perhaps we see the influence of Lippi’s beautiful Madonnas in the Madonna behind us. This was a chain of artistic greatness brought together by the city of Florence. But this painting isn’t just another beautiful Madonna and Child by Botticelli, there’s something special about it. Look at the buildings, look at their roofs. Look at the crow gables. These are northern roofs, the kind of roofs you would see in Copenhagen or Amsterdam or Bruges. They’re not roofs you would see in Florence or Naples or Rome. It’s quite possible that this painting was crafted by the master of gothic buildings. A northern painter who came south to work with Botticelli. And in a sense, this painting symbolizes the deep connections between the Northern and Southern Renaissance. The North, which gave us the detailed oil painting of van Eyck and van der Weyden. The South, which gave us linear perspective and the glories of da Vinci and Raphael. These two Renaissances came together in part because these two great urban civilizations, that of the Low Countries and that of central Italy, were tied so closely by common interests and by trade. In the 15th century, the North and the South looked very similar. They were both free places of commerce and creativity. Places where artistic genius flourished. Two centuries later, the North was still at it. Amsterdam was the center of a great trading empire, still churning out artistic masterpieces like Rembrandt’s Night Watch, while Florence had sunk into silence. One reason for this is political. Amsterdam had won its freedom in a hard fought 60 year revolt against their Hapsburg overlords. Florence had become a petty principality. The Medici’s had moved from being merchant princes, the first among equals who were eager to court popularity by sponsoring great artists, to becoming petty despots resting on their laurels. And so the greatness of Florence faded, and yet it is still here, that legacy of 15th century glory. Which reminds us of the miracles that happen when people come together and are connected by cities.