Cutting from an Antiphonary, with the Initial C ("Calicem"): the Host in a Monstrance on an Altar

Although the mass was the central act of Christian liturgy throughout the Middle Ages, the Catholic Church put renewed focus on the Eucharistic devotion in the thirteenth century. In 1264, Pope Urban IV added the feast of Corpus Domini (the Body of the Lord) to the church’s liturgical calendar; it is a movable feast falling on the Thursday after Trinity Sunday of each year. The initial “C” began the phrase “Calicem salutaris” (The cup of salvation), which was read during the office of Vespers on this feast day. The image within the initial, appropriate to this feast, shows a radiant monstrance displaying a consecrated host. The image refers to the widespread practice of displaying consecrated Eucharists in churches, so that Christians could adore Christ’s presence in the host even when a mass was not in progress.