(1) The chair or throne (thronos) of a bishop in his cathedral church, on which he presides at solemn functions. Originally the bishop's cathedra stood in the center of the apse, flanked on either side, though on a lower plane, by the benches of the assisting priests. A good idea of the arrangement may be had from the catacomb frescoes representing Christ seated on a throne surrounded by the apostles, whom He is instructing in their future duties, and in the fourth century mosaic in the apse of St. Pudenziana. The earliest type of bishop's throne consisted of a high-backed armchair, rounded at the top, made out of a single block of marble. The stone seats in the Roman catacombs of similar form were probably used by the bishop in the occasional services of the subterranean chapels. Wooden episcopal chairs were in use in Africa. The marble chair supporting the famous statue of St. Hippolytus (third century) is an excellent example of an ancient cathedra; the back has less than half the elevation of the thrones of the fourth and fifth centuries. In several Roman basilicas e.g. St. Petronilla, St. Bablina, and Sts. Nereus and Achilleus, a niche for the bishop's cathedra was constructed in the wall of the apse, but this arrangement was exceptional. An example of a cathedra with a perforated seat, like those used in the Roman baths, is preserved at Monte Cassino. The form and decoration of the most ancient of episcopal cathedrae were borrowed from paganism; one side of the chair of St. Hippolytus, however, is engraved with the saint's computation of the paschal cycle from the year 222 to 334. During the early centuries of Christianity it was customary for the bishop to deliver his sermon or homily while seated in his chair facing the congregation, but in the great basilicas of the Constantinian era, as well as subsequently, this arrangement became impracticable; it would have been extremely difficult in a large church to be heard from this location, particularly in a church where the altar was surmounted by a ciborium. St. John Chrysostom was accustomed to address his great audience from the better-adapted lector's ambon in front of the altar. It appears probable also that in some instances the episcopal cathedra was moveable, and thus could be placed near the chancel while the bishop addressed the congregation. This inference is suggested by the famous chair of Bishop Maximianus at Ravenna, the back of which, as well as the sides, contains sculptured ornamentation; if the chair was to remain stationary against the wall of the apse, the adornment of the back would have been superfluous. In a church ornamented with an iconostasis, a moveable episcopal chair became especially necessary if the bishop wished to preach from his throne, for otherwise he would be almost wholly shut out from view of the congregation. The two most famous ancient cathedrae still preserved are the chair of Maximianus mentioned above, and the chair of St. Peter. The latter, a moveable chair, stood in the time of Ennodius of Pavia (d.521), who alludes to it, in the baptistery of St. Peter's. During the pontificate of Alexander VII (1655-1667) it was encased in the bronze throne in the apse of the new St. Peter's, where it remained invisible till 1867. It was then, on the occasion of the eighteenth centenary of the martyrdoms of Sts. Peter and Paul, by order of Pius IX, removed from its bronze enclosure and exposed to the gaze of the faithful. De Rossi took advantage of the moment, and gave a description of the chair in his "Bullettino" (1867, 33 sqq.). The oak framework, in which four large rings are fastened, is regarded as of much greater antiquity than the other parts of the cathedra; the presence of the rings suggests the inference that originally the chair was one of the "sedes gestatoriae", which came into fashion in the reign of Claudius (41-54). The wear and tear of time, and the zeal of the relic-hunter, made extensive repairs necessary at a later period, perhaps in the reign of Charlemagne. The oak frame was reinforced by the insertion of pieces of acacia, and new panels of the same wood were made for the front and sides. The front panel is adorned with square slabs of ivory, disposed in three rows of six each, representing the labors of Hercules. Some of these slabs are placed upside down and were not, apparently, made for the places they occupy. The ivory ornaments of the back, on the contrary, are well adapted to the form of the chair; they represent the combats of animals, of centaurs and of men. In the center of the horizontal bar of the tympanum is the figure of an emperor, between two angels, variously supposed to represent Charlemagne, Charles the Bald, or an emperor of the seventeenth century. The ivories of the front panel are attributed to .the fifth century. The beautiful ivory chair of Bishop Maximianus (so called from the monogram in front, "Maximianus ep.") preserved in the sacristy of the cathedral at Ravenna is an excellent specimen of fifth- or sixth-century ivory carving. Until recentl y it was attributed to the pontificate of Bishop Maximianus of Ravenna (d. 556), but Venturi (Storia dell' Arte Ital., I, 466) attributes it rather to Maximianus of Constantinople (d. 431). The back is engraved with twenty four scenes from the life of Christ and the Blessed Virgin, the front represents St. John the Baptist with the four Evangelists, while on the sides the story of Joseph, in ten scenes, is depicted. Occasionally, the cathedra was covered by a baldachino, e.g. at Torcello and Grado. The marble cathedra of St. Mark, in his church at Venice, is of great antiquity (Secchi, La catedra di San Marco, Venice, 1835).

(2) The term cathedra was applied also to the see of a bishop. The earliest use of the word in this sense occurs in Tertullian, who speaks (De praescriptione, XXXVI) of "cathedrae Apostolorum" in allusion to Apostolic succession in episcopal sees. In the councils and ecclesiastical writings of the early Middle Ages such expressions as "cathedrae viduatae", "cathedrae principales", "cathedrae matrices" have a similar signification. For the feast of the "chair" or "cathedra" of St. Peter at Rome and at Antioch, see CHAIR OF PETER.

(3) Canon 41 of the Council of Aachen, held in 789, refers to the cathedral church as distinguished from other churches of a diocese as "principalis cathedrae"; the term for the official seat of the bishop is thus employed for the bishop's church. By a definition "ex cathedra" is meant a formal infallible decision of the pope, obligatory on all the faithful. See also, FALDSTOOL.

Haddan, in dictionary of Christian Antiquities, s. v. (London, 1875); I: Lowrie, Monuments of the Early Church, (New York, 1901); Venturi, Storia dell' Arte Italiana (Milan, 1901); Kraus, Gesch. der christl. Kunst (Freiburg, 1896); Kaufmann, Christl. Archäologie (Paderborn, 1905); de Fleury, La Messe, II, 147 sqq.

MAURICE M. HASSETT