The part of the church reserved for the higher clergy was known
in antiquity by various names, among them presbyterium, because
of its occupation during the liturgical functions by the priests
attached to a church, arranged in a half-circle round the
bishop. The presbytery was also known as apsis, exedra, concha,
designations referring to its form; bema from the fact that it
was elevated above the level of the nave and in consequence
reached by a stairway of a few steps; tribuna because of its
location and general resemblance to the tribunal in civil
basilicas whence the magistrates administered justice. These
various names were, in the Middle Ages, mostly superseded by the
term choir, which in turn yielded to the modern term sanctuary.
The presbytery was separated from the rest of the church by
rails (cancelli). Eusebius, in his dedication oration at Tyre
(Church History X.4), describes this feature of the church and
its objects: "the Holy of Holies, the altar", he explains, was
inclosed with wooden lattice-