AII80421: The Study of Federigo da Montefeltro, Duke of Urbino, clockwise from TL: Greek philosophers Plato (c.427-347 BC) and Aristotle (384-322 BC); Ptolemy, astronomer (c.90-168); Boethius, philosopher (c.480-524); St. Augustine of Hippo (354-430); St. Ambrose (c.339-397); St. Jerome (342-420); Pope Gregory the Great (540-604) (panel, photographs replace some originals in Louvre), Joos van Gent (Joos van Wassenhove) (fl.1460-75) / Bridgeman Images