The winged ox has been traditionally associated with Saint Luke and has multiple meanings, for the ox is the king of domesticated animals and, since winged, a heaven bound messenger. The four symbols, known collectively as the Tetramorph have been traced to an Old Testament passage in the book of the prophet Ezekiel and appear in Christian iconography as early as the 5th century AD. The stamp image is from one of the illuminated manuscripts of the Lichfield Gospels, currently housed in the Lichfield Cathedral in Ireland, These gospels, older than the famous Book of Kells, date from the 8th century.