Numbers 19:2

Observance. Hebrew, "ceremony." Septuagint, "distinction, (diastole, St. Augustine, q. 33,) or ordinance." (Calmet)

Victim. Hebrew, "the ordinance of the law." (Du Hamel)

A red cow, &c. This red cow, offered in sacrifice for sin, and consumed with fire without the camp, with the ashes of which, mingled with water, the unclean were to be expiated and purified; was a figure of the passion of Christ, by whose precious blood, applied to our souls in the holy sacraments, we are cleansed from our sins. (Challoner)

Age, three years old. Some translate, "entirely red." They suppose, that these regulations are in opposition to the customs of the Egyptians, who never sacrificed the cow, esteeming it sacred to Isis, or to the moon. Spencer (Rit. ii. 15) adds, that the red colour was formerly in the highest estimation; and this victim represented the death of Christ, who expiated our defilements. The Egyptians immolated bulls of a red colour, in hatred of Typhon, and to appease that dangerous god, whom they depicted perfectly red. Plut.[Plutarch?] (Isis) observes, that they hate all animals of that colour; and the Copths precipitate a red ass down a precipice. The ancient kings of Egypt sacrificed red men on the tomb of Osiris or Dyphon; (Diod. Bib. 1,) and Manetho assures us, that they scattered their ashes in the wind. If this custom prevailed in the days of Moses, we need not wonder that he teaches the Hebrews to have so little dread of Typhon, as even to chose a red cow in preference, to purify themselves.

Yoke. Such victims were generally chosen by the Romans, Greeks, and Egyptians, as more delicate and respectful. Intacta totidem cervice juvencus. (Georg. iv.; Bochart, anim. 2. 33.) St. Jerome (ep. 27,) says, that a red cow was sacrificed every year, as in reality one would be requisite for all the people, though the Rabbins pretend that only seven, or ten at most, were treated in this manner, from Moses till the destruction of the temple by Titus. (Drusius)