The Targum Pseudo-Jonathan on Exodus 28:19 lists the third row of the breastplate: ligure, and agate, and amethyst, engraved with Gad, Asher, and Issachar. The tribes of this row were, in Jacob's blessings, the tribes of abundance and depth. Gad would be a warrior, a troop shall overcome him (Genesis 49:19). Asher's blessing was his bread shall be fat, and he shall yield royal dainties (Genesis 49:20). Issachar bent his shoulder to bear and became the tribe of scholars who knew the seasons.

The Sages treated the amethyst — the final stone in this row — as especially suggestive. Its Aramaic name, ein egla, means calf's eye, and some traditions linked it to Issachar, whose sons were said to have calm, clear-sighted minds fit for Torah study. The third row, in other words, became a row of inner life. Warrior, host, and scholar stood together, three different ways of sustaining a people.

The takeaway is that the middle of the breastplate was reserved for the middle work of a nation — the unspectacular labor of feeding, protecting, and studying — without which kings and judges have nothing to govern.