ISB ~ Acts 1 v26

cast lots:A process of selection using marked sticks or stones. It was not a game of chance but a venerated means of discerning God’s will (Lev 16:7-10; Prov 16:33). It was also a means for assigning ritual duties to Levitical priests serving in the Temple (1 Chron 24:31). Matthias: His enrollment with the Eleven reconstitutes the original number of the Twelve, who represent the restored tribes of Israel gathered around the Messiah (Lk 22:30; Rev 21:12-14; CCC 765). For Luke, the main point of the election is to recover the symbolic number 12, as seen in the fact that Matthias never again appears in the narrative of Acts. Note that the Twelve belong to the period of the Church’s founding and do not represent an ongoing institution in the life of the Church (no mention is made in Acts 12:2 of a replacement for the Apostle James after his martyrdom).