A kind of portrait of a sacred person with a formal pose and exaggerated spiritual expression which spread through the Christian world from the mid 6th century AD onwards. Usually icons are painted on wood and housed in jeweled and highly ornate mounts. Some became so powerful as objects of devotion as to cause a rift in the Christian church, known as the iconoclastic dispute, where icons were banned in the Byzantine empire from AD 726, although the Latin church continued to allow their use. They remain a central component of the material culture of the Orthodox church.