Bede the Venerable — as excerpted in the Catena Aurea on Luke 1:23-25

“Now mystically by Zacharias may be signified the Jewish Priesthood, by Elisabeth the law itself; which, well administered by the teaching of the Priests, ought to have borne spiritual children to God, but was not able, because the Law made no one perfect. (Heb. 7:19, 1 Tim. 1:8.) Both were just, because the law is good, and the Priesthood for that time holy; both were well stricken in years, because at Christ’s coming both the Law and Priesthood were just bending to old age. Zacharias enters the temple, because it is the priest’s office to enter into the sanctuary of heavenly mysteries. There was a multitude without the doors, because the multitude cannot penetrate mysteries. When he places frankincense on the altar, he discovers that John will be born; for while the teachers are kindled with the flame of divine reading, they find the grace of God flow to them through Jesus: and this is done by an angel, for the Law was ordained by angels. (Gal. 3:19.)”