Catechism of the Catholic Church

The Church is apostolic because she is founded on the apostles, in three ways: (75, 171, 880, 1575) - she was and remains built on "the foundation of the Apostles," the witnesses chosen and sent on mission by Christ himself; - with the help of the Spirit dwelling in her, the Church keeps and hands on the teaching, the "good deposit," the salutary words she has heard from the apostles; - she continues to be taught, sanctified, and guided by the apostles until Christ's return, through their successors in pastoral office: the college of bishops, "assisted by priests, in union with the successor of Peter, the Church's supreme pastor": > You are the eternal Shepherd who never leaves his flock untended.Through the apostles you watch over us and protect us always.You made them shepherds of the flock to share in the work of your Son....