strictly defined as choir and sanctuary, does not fill the full width of a medieval church, there will usually be some form of low wall or screen at its sides, demarcating it from the ambulatory or parallel side chapels. As well as the altar, the sanctuary may house a credence table and seats for officiating and assisting ministers. In some churches, the congregation may gather on three sides or in a semicircle around the chancel. In some churches, the pulpit and lectern may be in the chancel, but in others these, especially the pulpit, are in the nave. The presbytery is often adorned with chancel flowers. Name The word "chancel" derives from the French usage of chancel from the Late Latin word cancellus ("lattice"). This refers to the typical form of rood screens. The chancel was formerly known as the presbytery, because it was reserved for the clergy. History In Early Christian architecture the templon was a barrier dividing off the sanctuary from the rest of the church; in Eastern Christianity this developed into different arrangements from those of the Western church, with the sanctuary often not visible to the congregation. In the West the ciborium, an open-walled but usually roofed structure sheltering the altar, became common, and was originally fitted with curtains that were drawn and pulled back at different points in the Mass, in a way that some Oriental Orthodox churches still practice today. A large (or "deep") chancel made most sense in monasteries and cathedrals where there was a large number of singing clergy and boys from a choir school to occupy the choir. In many orders "choir monk" was a term used to distinguish the educated monks who had taken full vows, or were training to do so, from another class, called "lay brothers" or other terms, who had taken lesser vows and mostly did manual tasks, including farming the monastery's land. These usually sat in the nave, with any lay congregation. Following the exposition of the doctrine of transubstantiation at the fourth Lateran Council of 1215, clergy were required to ensure that the blessed sacrament was to be kept protected from irreverent access or abuse; and accordingly the area of the church used by the lay congregation was to be screened off from that used by the clergy. This distinction was enforced by the development of canon law, by which the construction and upkeep of