Elijah's Return as Herald of Final Unification
A closing prophecy in Malachi about a family-reconciling messenger became, through Elijah's unique biblical status as a prophet who never died, the anchor of an entire Kabbalistic tradition of ongoing mystical visitations.
The book of Malachi ends by promising that Elijah the prophet will be sent before "the great and terrible day of the LORD," specifically to reconcile parents and children before that day arrives. Elijah is uniquely suited for this liminal role because, according to 2 Kings, he did not die but ascended to heaven in a whirlwind, leaving him — uniquely among biblical figures — able to move between worlds rather than waiting, like everyone else, for resurrection. Kabbalistic messianism built an entire literature around this status, including recorded traditions of direct communications from Elijah to later mystics, most famously the maggid experiences described by the sixteenth-century legal scholar and Kabbalist Joseph Karo. In this framework, Elijah's periodic visitations are read as advance signals of the larger process of tikkun nearing completion — a final unification not just of estranged parents and children, as Malachi's plain text specifies, but of the scattered sparks and divided sefirot that the whole system has been working to reassemble.
Behold, I will send you Elijah the prophet.
Malachi