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Sacraments › … › II. The Sacrament of Holy Orders in the Economy of Salvation
The priesthood of the Old Covenant
Instituted to proclaim the Word of God and to restore communion with God by sacrifices and prayer, this priesthood nevertheless remains powerless to bring about salvation, needing to repeat its sacrifices ceaselessly and being unable to achieve a definitive sanctification, which only the sacrifice of Christ would accomplish.
Source: Catechism of the Catholic Church (Vatican.va)