John Chrysostom : For why (tell me) is the book of the testament sprinkled? "For" (he says) "when Moses had spoken every precept to all the people according to the law, he took the blood of calves, with water, and scarlet wool, and hyssop, and sprinkled both the book itself and all the people, saying, This is the blood of the testament, which God hath enjoined unto you." Tell me then why is the book of the testament sprinkled, and also the people, except on account of the precious blood, figured from the first? Why "with hyssop"? It is close and retentive. And why the "water"? It shows forth also the cleansing by water. And why the "wool"? This also [was used], that the blood might be retained. In this place blood and water show forth the same thing, for baptism is His passion. — Homily on Hebrews 16 Oecumenius : "For when every commandment had been spoken." For after he spoke the commandment, then Moses sprinkled the blood. "according to the law." As He says, God legislated, according to the law of God. Or of every command according to the law, these, of the legislated one. "taken the blood of calves." This blood was a type of the blood of God and our Savior, who cleansed us from all stain. "with water." Water was the figure of baptism. "and scarlet wool and hyssop." Wool and hyssop were used for their preservation. Indeed, hyssop, being dense and tender, retained and sprinkled blood, and wool likewise. Scarlet, however, was wool so that by its very color it would bear the type of the blood of Christ. "the book itself." The book was a type of the faithful, those who have the law of God within themselves. — The Pseudo-Oecumenian Catena on Hebrews Tertullian : One of these goats was bound with scarlet, and driven by the people out of the camp into the wilderness, amid cursing, and spitting, and pulling, and piercing, being thus marked with all the signs of the Lord's own passion; while the other, by being offered up for sins, and given to the priests of the temple for meat, afforded proofs of His second appearance, when (after all sins have been expiated) the priests of the spiritual temple, that is, the church, are to enjoy the flesh, as it were, of the Lord's own grace, whilst the residue go away from salvation without tasting it. — Against Marcion Book III Theodoret of Cyrus : Since the divine nature is immortal, through the blood of the victims he realized the type of death and confirmed the covenant. Since God the Word became man and took a mortal body, there was no longer need of brute beasts as offerings; instead, he confirmed the new covenant with his own blood, the type corresponding to the shadow and the reality to the body. The water was a type of baptism, the blood of brute beasts the saving blood, the heat of the hyssop the grace of the divine Spirit, the scarlet wool the new garment, the piece of cedar (being a wood that does not rot) the impassible divinity, the ashes of a heifer the suffering of humanity. — INTERPRETATION OF Hebrews 9