OSBERT de CLARE. - English Benedictine theologian of the 12th century, born at Clare (county of Suffolk). He became a monk of Westminster Abbey and, about 1136, prior. He was an ardent, learned, and skilful defender of the doctrine of the Immaculate Conception of Mary and promoted the proclamation of the feast, which was strongly opposed by Ruggero, bishop of Salisbury, and Bernardo, bishop of St. David, and many others, although the feast had been observed in England before the Norman invasion (1066).
The Council of London in 1129 decided in favour of the feast, and Gilberto, bishop of London, adopted it in his diocese. O. was a friend of Anselmo (the Saint’s nephew), abbot of Bury St. Edmund. About 1141 he was sent to Rome by King Stefano (1135–54), together with his abbot, to ask the Pope for the canonization of King Edoardo the Confessor. O. deserves great honour for his Epistles to Anselmo and to Warino, dean of Worcester, and for the sermon De Conceptione Sanctae Mariae, in which he set forth the theology of the Immaculate Conception accurately and skilfully. He also wrote the lives of Saints Edoardo, Edmondo, and others. He has sometimes been confused with the hagiographer Osbern (who died about 1090).