CORPUS CHRISTI, FEAST OF, a festival of the Roman Catholic Church in honour of the Real Presence of Christ in the Eucharist, observed on the Thursday after Trinity Sunday (Lat. f eeturn corporis Christi, Fr. fête-Dieu or fete du saint-sacrement, Ger. Fronleichnams f est) . The institution of this feast is due to St. Juliana, prioress of Mont Cornillon near Liege (1222-58), whose veneration for the Blessed Sacrament was intensified by a vision, and who persuaded Robert de Torote, bishop of Liege, to order the festival for his diocese in 1246. It did not spread, how ever, until in 1 261 Jacques Pantaloon, formerly archdeacon of Liege, became pope as Urban IV. In 1264 Urban ordered the whole Church to observe the feast, for which a new office (still in use) was written by St. Thomas Aquinas ; but the well-known story of the miracle of Bolsena, which is supposed to have has tened the pope's decision, is not supported by contemporary evi dence, and is probably a later adaptation of a type of legend which occurs at least as early as the 12th century. Owing per haps to Urban's death soon afterwards (Oct. 2, 1264), his order was ignored in most countries until after its confirmation by Clement V. at the council of Vienna in 1311. By the middle of the 14th century the festival had found general acceptance; and in the 15th century it became in effect the principal feast of the Church. The procession of the Host, its most prominent feature (though not part of the original ritual), became a gorgeous pag eant, in which sovereigns and princes took part, as well as magis trates and members of trade and craft gilds ; and was followed by miracle-plays and mysteries performed by members of the gilds.
The rejection of the doctrine of transubstantiation at the Re formation naturally involved the suppression of the festival, as a religious observance, in the reformed Churches; but the mystery plays survived for a time in places.