Holy Orders is the sacrament through which the mission Christ entrusted to his apostles continues to be exercised in the Church until the end of time: thus it is the sacrament of apostolic ministry. The sacrament of orders includes three degrees: the diaconate, the presbyterate, and the episcopate.
Through the laying on of hands, and the prayer of consecration by the bishop, a man is configured to Christ the high priest, and given sacred power to teach, govern and sanctify the faithful.
In the ecclesial service of the ordained minister, it is Christ himself who is present to his Church as Head of his Body, Shephard of his flock, high priest of the redemptive sacrifice, Teacher of Truth. This is what the Church means by saying that the priest, by virtue of the sacrament of Holy Orders, acts in persona Christi Capitis.
The ministerial priesthood has the task not only of respresenting Christ - Head of the Church - before the assembly of the faithful, but also of acting in the name of the whole Church when presenting to God the prayer of the Church, and above all when offering the Eucharistic sacrifice (CCC 1552).
For more information on the sacrament of Holy Orders please contact the Vocations Office of the Archdiocese of Toronto