The Annunciation, with Saint Emidius

Crivelli painted this for Ascoli Piceno to celebrate the town's right of self-government, granted by Pope Sixtus IV in 1482. In the foreground, on the threshold of Mary's house, Crivelli placed a large cucumber and an apple side by side. The cucumber appears in many of his religious paintings; scholars have argued for 500 years about why. Resurrection, Eden fruit, phallic symbol, civic agriculture — nobody is sure. Now at National Gallery, London @nationalgallery