Bede the Venerable
Catena Aurea · Markusevangelium 3
And he goeth up into a mountain, and calleth unto him whom he would: and they came unto him. And he ordained twelve, that they should be with him, and that he might send them forth to preach, And to have power to heal sicknesses, and to cast out devils: And Simon he surnamed Peter; And James the son of Zebedee, and John the brother of James; and he surnamed them Boanerges, which is, The sons of thunder: And Andrew, and Philip, and Bartholomew, and Matthew, and Thomas, and James the son of Alphæus, and Thaddæus, and Simon the Canaanite, And Judas Iscariot, which also betrayed him.
(ubi sup.) For as a sacrament of this the children of Israel once used to encamp about the Tabernacle, so that on each of the four sides of the square three tribes were stationed. Now three times four are twelve, and in three bands of four the Apostles were sent to preach, that through the four quarters of the whole world they might baptize the nations in the name of the Father, the Son, and the Holy Ghost. It goes on: And he gave them power, &c. That is, in order that the greatness of their deeds might bear witness to the greatness of their heavenly promises, and that they, who preached unheard-of things, might do unheard-of actions.