L'Agonie au jardin des Oliviers

This is a small panel, barely a foot tall, and Correggio painted it around 1524 as an experiment in darkness. The scene is night on the Mount of Olives. Christ kneels in prayer while his three companions sleep, and an angel leans in from the left. Almost the only light comes off Christ himself, brighter than the coming dawn, catching the folds of his robe and the sleeping men. Vasari, who saw it, called it one of the rarest and most beautiful things Correggio made. Centuries later it reached Spain, and after the Peninsular War the Spanish king Ferdinand VII gave it to the Duke of Wellington. It hung at Apsley House as the Duke's own favourite among his pictures.