As the successor to St. Peter, the pope's role is to be an earthly father to the people of God (The word pope means "father.") He is also the shepherd appointed by the greatest Shepherd of them all - Jesus (Jn 21:15-17). As Peter led the apostolic college, so his successor, the pope, leads the episcopal college of bishops (Catechism 880). In this capacity, he confirms his brother bishops and the priests in Faith (Lk 22:32), and works with them to spread the Gospel and to pastor the flock of God (Mt 28:18-20; 1 Pt 5:1-3; Catechism 882). The document Lumen Gentium of the Second Vatican council (1962-1965), speaks of the pope's role as the Church's "principle of unity." This means that he has "full, supreme, and universal power over the whole Church" as the successor of St. Peter and head of the college of bishops (Lumen Gentium 22; Catechusm 882). The pope protects the deposit of faith given to the Church two thousand years ago by Jesus. He does not make new doctrine, nor can he change a doctrine to mean something different from what it meant in the past (Catechism 891). His role is to pass on the faith to the Church (Jude 3).