– There is an important connection between this and the matter of the revelation of Mashiach. Normally, we understand that the context of the prayer deals with the blessing of abundant rain and the resultant physical blessings of G‑d for bounty and prosperity. It is because we understand the need for rain that we ask G‑d for His blessings and our prayers are answered with beneficial rains.
So, when we recite, “He causes the wind to blow and the rain to fall,” for the third time tonight we establish the chazakah connected with the acceptance of G‑d’s benevolence in matters of abundant sustenance, as well as the blessing in all our material needs, children and life-health, all with abundance.
There is however, another, esoteric explanation of this prayer which deals with the subject of redemption. When the Torah told us:
“G‑d’s spirit moved on the waters surface,” (Bereishis 1:2)
the Midrash commented:
“This is the spirit of the King Mashiach.” (Bereishis Rabbah 2:4)
In this context the sentence “Mashiv Haruach” reads thusly: “He makes the spirit of Mashiach come down into the physical (geshem)”: a soul clothed in a body in the material world.
It follows that on this night of Simchas Torah we establish the chazakah — the presumption — for the spirit of Mashiach to descend into the corporeal world.
From the Rebbe’s talk on the Eve of Simchas Torah, 5746.