In the 11th century the Papacy was weak and a break between Rome (Rome I) and Constantinople, Byzantium (Rome II) took place. These two branches of the Church spoke different languages (Latin in the west and Greek in the east). There was a political struggle for domination between the Latin Pope and the Greek Patriarch, and there were also certain doctrinal differences. The latter including disagreement over the unity of the Trinity -- Father, Son and the Holy Spirit in the western church and minimization of the role of the Holy Spirit in the eastern church, as well as the fact that priestly celibacy was observed by Rome and rejected by Byzantium. In 1054, the quarrel gained so much intensity that a great Schism took place.