The Catechism of the Catholic Church devotes a number of pages to its discussion of the Sacrament of Holy Orders. It remarks three degrees of the sacrament: deacons, priests and bishops, and describes the sacramental tasks properly assigned to each (see No. 1554). Bishops, because they represent the apostles, exercise a ministry of special honor — one that extends back to the earliest days of our faith, and, through an unbroken tradition, connects us to the early Church.
Priests share in this ministry, although to a lesser degree, and a document of the Second Vatican Council, Presbyterorum Ordinis, describes both the priest’s ministry and the authority by which he receives it from the bishop. The Catechism pulls from this document to teach that priests “depend on the bishops in the exercise of their own proper power” and “so are configured to Christ . . . in such a way that they are able to act in the person of Christ the head” (see Nos. 1563-1564).
The point here is to connect the Sacrament of Holy Orders with Jesus, the High Priest. For this reason, too, the bishop is the ordinary minister of the Sacrament of Confirmation. This is to remind us of the apostolic origins of the sacrament (see Catechism, No. 1313)