Catechism of the Catholic Church §1545 — excerpt
The redemptive sacrifice of Christ is unique, accomplished once for all; yet it is made present in the Eucharistic sacrifice of the Church. the same is true of the one priesthood of Christ; it is made present through the ministerial priesthood without diminishing the uniqueness…
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: St. Thomas Aquinas, Hebr. 8, 4