The Torah counts the sons of Jacob: "the sons of Jacob were twelve" (Genesis 35:22). Six from Leah: Reuben, Simeon, Levi, Judah, Issachar, Zebulun; two from Rachel: Joseph and Benjamin; two from Bilhah, Rachel's maidservant: Dan and Naphtali; two from Zilpah, Leah's maidservant: Gad and Asher. At the end of his life Jacob blesses them one by one, and the text concludes: "all these are the tribes of Israel, twelve; and this is what their father spoke to them, and he blessed them" (Genesis 49:28). Moses in turn blesses them before his death (Deuteronomy 33). Each entry follows these two blessings, after the name the mother gave the child (Genesis 29, 30 and 35).
The number twelve holds even when the list changes. Jacob adopts Joseph's two sons: "Ephraim and Manasseh shall be mine like Reuben and Simeon" (Genesis 48:5). And the tribe of Levi is not counted with the others: it encamps around the Tabernacle, which it carries and guards (Numbers 1:47 to 53). With Levi set apart and Joseph doubled, we find twelve again.
On the High Priest's breastplate, twelve stones in four rows bear "the names of the sons of Israel, twelve according to their names" (Exodus 28:21). Rashi specifies that the order of the stones is the order of birth, and the Targum attributed to Jonathan names the tribes row by row. The identification of the stones, however, remains uncertain: translations disagree, and the Targum itself gives other names than the ones read today.
In the desert the tribes encamp in four camps of three around the Tent of Meeting (Numbers 2): Judah to the east, Reuben to the south, Ephraim to the west, Dan to the north, the Levites in the middle. Rashi explains that each banner had the color of its tribe's stone; Ibn Ezra reports, in the name of the ancients, a lion on Judah's banner, the figure of a man on Reuben's, an ox on Ephraim's, an eagle on Dan's. Ramban links this camp to a phrase of Sefer Yetzirah: six directions, and "the holy palace set in the middle."
Finally, Sefer Yetzirah counts twelve simple letters, which form the twelve months (5:2). It names no tribe. The link between months and tribes comes from later authors, and it varies: according to the order of the Ari, reported by the Shem MiShmuel and the Pri Tzaddik, the months follow the order of the banners, from Nissan for Judah to Adar for Naphtali; according to the order of birth, which the Shem MiShmuel also cites, Nissan goes to Reuben and Iyar to Simeon. The app follows the order of the banners.
Keep this: in each of these texts, the twelve are arranged around a center, the father who blesses, the priest's breastplate, the Tabernacle. No tribe is sufficient to itself; it is the whole that bears the name of Israel.
