Three things jump readily to mind.
Ordination, or the reception of orders, is a religious and liturgical act that can be thought of as a consecration, a blessing or a sacrament.
Today the word "ordination" is reserved for the sacramental act which integrates a man into the order of bishops, presbyters, or deacons, and goes beyond a simple election, designation, delegation, or institutionby the community, for it confers a gift of the Holy Spirit that permits the exercise of a "sacred power" (sacra potestas)which can come only from Christ himself through his Church. (Catechism of the Catholic Church, #1538)
Ordination involves the laying on of hands by the bishop, along with a prayer of consecration. These constitute the visible signs of ordination.
The whole Church is a priestly people. Through Baptism all the faithful share in the priesthood of Christ. This participation is called the "common priesthood of the faithful." Based on this common priesthood and ordered to its service, there exists another participation in the mission of Christ: the ministry conferred by the sacrament of Holy Orders, where the task is to serve in the name and in the person of Christ the Head in the midst of the community.
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