The figurative reason of these things was that Christ was foreshadowed both by the calf, on account of His power; and by the ram, because He is the Head of the faithful; and by the he-goat, on account of “the likeness of sinful flesh” (Rom. 8:3). Moreover, Christ was sacrificed for the sins of both priests and people: since both those of high and those of low degree are cleansed from sin by His Passion. The blood of the calf and of the goat was brought into the Holies by the priest, because the entrance to the kingdom of heaven was opened to us by the blood of Christ’s Passion. Their bodies were burnt without the camp, because “Christ suffered without the gate,” as the Apostle declares (Heb. 13:12). The scape-goat may denote either Christ’s Godhead Which went away into solitude when the Man Christ suffered, not by going to another place, but by restraining His power: or it may signify the base concupiscence which we ought to cast away from ourselves, while we offer up to Our Lord acts of virtue.
With regard to the uncleanness contracted by those who burnt these sacrifices, the reason is the same as that which we assigned (ad 5) to the sacrifice of the red heifer.
Reply Obj. 7: The legal rite did not cleanse the leper of his deformity, but declared him to be cleansed. This is shown by the words of Lev. 14:3, seqq., where it was said that the priest, “when he shall find that the leprosy is cleansed,” shall command “him that is to be purified”: consequently, the leper was already healed: but he was said to be purified in so far as the verdict of the priest restored him to the society of men and to the worship of God. It happened sometimes, however, that bodily leprosy was miraculously cured by the legal rite, when the priest erred in his judgment.