The Sacrament of Holy Orders is the continuation of Christ's priesthood, which He bestowed upon His Apostles ("the Sacrament of Apostolic Ministry"). "Ordination" comes from the Latin word ordinatio, which means to incorporate someone into an order. In the Sacrament of Holy Orders, a man is incorporated into the priesthood of Christ, at one of three levels: the episcopate (bishop), the priesthood, or the diaconate. A man cannot demand ordination; the Church has the authority to determine eligibility for the Sacrament. Because of his role as a successor to the Apostles, who were themselves successors to Christ, the bishop is the proper minister of the Sacrament.
For more information: Contact the Catholic Diocese of Cleveland - Office of Vocations