Lippo Memmi

In 1333 two painters from Siena signed a single altarpiece together, and scholars have argued ever since about who did what. The names on the original frame are Simone Martini, the most celebrated painter of the city, and Lippo Memmi, his brother-in-law. Simone had married Lippo's sister, and the two men shared a workshop.

The painting is the "Annunciation with Saint Margaret and Saint Ansanus," now in the Uffizi gallery in Florence. Against a ground of gold, a startled Virgin recoils from a kneeling angel, in the swaying, elegant manner later called International Gothic. The usual guess is that Simone painted the central pair while Lippo handled the two flanking saints and the small prophets in the roundels above, though no document proves it.

Lippo worked on his own too. In the hill town of San Gimignano, famous for its stone towers, he painted a large "Maestà," the Virgin enthroned among saints, in the town hall, following closely a model Simone had set a few years earlier. When Simone left around 1336 for the exiled papal court at Avignon in France, Lippo stayed behind in Siena and kept the workshop running.