This week Neil MacGregor's world history as told through objects is describing how people expressed devotion and connection with the divine in the 14th and 15th centuries. Today he is with an icon from Constantinople that looks back in history to celebrate the overthrow of iconoclasm and the restoration of holy images in AD 843 - a moment of triumph for the Orthodox branch of the Christian Church. This icon shows the annual festival of orthodoxy celebrated on the first Sunday of Lent, with historical figures of that time and a famous depiction of the Virgin Mary. The American artist Bill Viola responds to the icon and describes the special characteristics of religious painting. And the historian Diarmaid MacCulloch describes the often troubled relationship between the Church and the images it has produced. Producer: Anthony Denselow.