שרי אשתך לא תקרא שמה שרי כי שרה שמה וגו׳

The maamar opens with G‑d’s instruction to Abraham to change his wife’s name from Sarai (spelled with a final yud) to Sarah (spelled with a final hei). The Alter Rebbe states the premise: the purpose of this change was to give her the ability to bear a child.

The Midrash says that as Sarai she could not give birth, but as Sarah she could. This raises a difficulty: in Kabbalah the letter yud stands for Chochmah and the letter hei for Binah, and Chochmah is the higher faculty. Why would exchanging a higher letter for a lower one bring about the ability to give birth?

The question is sharpened. Chochmah is called ayin, ‘nothing’, because it is the first flash of insight before anything is defined; bringing something new into being, ‘something from nothing’, is rooted there. Binah, where the idea is developed and takes on definite shape, is called yesh, ‘something’, an existence already there.

So the change seems backwards: to give Sarah the power to give birth, the yud, the letter of Chochmah and the source of new existence, was taken away, and the hei of Binah was put in its place.

The answer begins. Abraham and Sarah correspond to two levels of Chochmah: Abraham to the higher Chochmah, rooted in the Chochmah of Atzilus, and Sarah to the lower Chochmah. What is true of how birth works at the higher level is not true of the lower one, as the next paragraph explains.

Here the answer is given. At the higher level (Abraham’s), a genuinely new existence comes about only through tzimtzum, the self-concealment of the Infinite Light. Without such contraction, nothing separate could arise.

If the Infinite Light spread forth as it truly is, no finite existence could come into being, however many stages of descent it passed through, since its nature is to have no end. That is why, at the higher level, the yud, a single contracted point, is the letter of birth.

At the lower level, Sarah’s, it is the reverse. There the light is already limited, so further contraction would leave only darkness and concealment; new existence comes about precisely through spreading out and expansion. The hei, a letter with breadth and length, expresses that expansion.

The text’s own parenthetical support: the yud is drawn with three tips, an upper, a middle and a lower one. The lower tip is the source of Binah, and it depends on the upper tip, which shows that the spreading out associated with Binah draws its power from what is above it.

A further support is the shape of the two hei’s in the Name Havayah, a letter that spreads out in width and length. The text then raises an objection: Abraham too received a hei, since the Midrash says ‘Abram does not beget’ but Abraham does; yet Abraham is the higher Chochmah, for whom birth should come through contraction, not expansion.

The answer: Abraham’s hei was for what the verse states explicitly, that he would be ‘the father of a multitude of nations’, like ‘the souls they had made in Charan’, which our tradition understands as the people Abraham and Sarah drew to the service of G‑d. That is elevation from the side opposed to holiness, which requires expansion outward.

For the birth of Isaac, who belongs wholly to the side of holiness, Abraham did not need the hei, because holiness is by nature self-nullification (bittul), not spreading forth. So at Abraham’s level the birth of a holy child still comes through the contraction of the yud.

Sarah, however, being the lower Chochmah, did need the hei for Isaac’s birth, since at her level new existence comes through expansion. The text refers the reader to a maamar in Parshas Chayei Sarah, ‘Yegaleh lan ta’amei’, for more on this.