From “Homily 1 in Advent,” 3 (ca. 730)
We should not wonder that, according to the historical sense, Elizabeth is said to be the cousin of Mary, since earlier we are told that Mary arose from the house of David., and that Elizabeth arose from the daughters of Aaron. Now we read that it was from the tribe of Judah, from which David arose, that Aaron himself received his wife, namely Elizabeth… of the tribe of Judah when they came out of Egypt [Exod. 6:3] …
In addition, regarding the later Davidic king, we read that Johoiada, the high priest had a wife of the kingly tribe. Hence it is proven that both tribes — the priestly tribe and the royal tribe — were always joined to each other by blood relationship. However it was possible for a joining of this sort to occur in a more recent time too, with the giving of women in marriage from tribe to tribe, so that it is clearly a fact that the blessed mother of God, who descended from the royal tribe, had a blood relationship by birth with the priestly tribe, and this was most aptly fitting to heavenly mysteries.
Now, when the mediator between God and human beings appeared in the world, it was fitting that he had his physical origin from both tribes because in the humanity which he assumed he would possess both the roles of priest and king. On the one hand, the gospel bears witness to his royal power, by which he bestowed an everlasting reign on his elect, “for he will reign in the house of Jacob forever, and of his kingdom there will be no end.” Concerning his dignity as high priest, on the other hand, in which he deigned to offer the sacrificial offering of his flesh for our redemption, the prophet bears witness, as he says, “You are a priest forever according with the order of Melchizedek.”
The Venerable Bede (ca. 673-735) was an English monk, teacher, and scholar, one of the most influential figures of the early Middle Ages. He was famed in his lifetime for his Biblical commentaries, and is best known today for his great history of the English church and people. His feast day is May 25. This translation is from Lawrence Martin and David Hurst, eds, Homilies on the Gospels: Book One, Advent to Lent (Athens, OH: Cistercian Publications, 1991).