Holy Orders is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time. It is the sacrament of apostolic ministry. In the ministry of the ordained priest, it is Christ himself who is present to his Church as Head of his body, Shepherd of his flock, High Priest of the redemptive sacrifice, and Teacher of the truth. This is what the Church means by saying that the priest, by virtue of the sacrament of Holy Orders, acts in persona Christi –– that is, in the person of Christ.