from Thomas Cahill’s Heretics and Heroes: In a collection of travel essays published in 1925, Aldous Huxley had called Piero [della Francesca’s] Resurrection, the fresco that decorates the Museo Civico of Sansepolcro, “the greatest picture in the world.” In the last days of World War II, as British soldiers began shelling Nazi-occupied Sansepolcro with the…