Thomas Aquinas

“ Further, the priesthood of Christ has a greater similarity to the Jewish priesthood, instituted by God, than to the priesthood of the Gentiles, by which the demons were worshiped. Now in the old Law man was never offered up in sacrifice: whereas this was very much to be reprehended in the sacrifices of the Gentiles, according to Ps. 105:38: "They shed innocent blood; the blood of their sons and of their daughters, which they sacrificed to the idols of Chanaan." Therefore in Christ's priesthood the Man Christ should not have been the victim. ”

“ Now the proper effect of priesthood is that which results from the sacrifice itself. But Christ obtained a result from His passion, not as by virtue of the sacrifice, which is offered by way of satisfaction, but by the very devotion with which out of charity He humbly endured the passion.
Reply to Objection 3: A figure cannot equal the reality, wherefore the figural priest of the Old Law could not attain to such perfection as not to need a sacrifice of satisfaction. ”

“ Hierarchical power appertains to the angels, inasmuch as they also are between God and man, as Dionysius explains (Coel. Hier. ix) , so that the priest himself, as being between God and man, is called an angel, according to Malachi 2:7: "He is the angel of the Lord of hosts." Now Christ was greater than the angels, not only in His Godhead, but also in His humanity, as having the fulness of grace and glory. ”

“ The fact that Christ's manhood was holy from its beginning does not prevent that same manhood, when it was offered to God in the Passion, being sanctified in a new way---namely, as a victim actually offered then. ”

“ Further, every victim, through being offered to God, is consecrated to God. But the humanity of Christ was from the beginning consecrated and united to God. Therefore it cannot be said fittingly that Christ as man was a victim. ”