The Zohar provides a profound answer to the often asked question of why our rabbis traditionally taught that the Jewishness of newborn children is determined by the mother; and not by the father.
The simplest answer is that one can determine a child’s mother most more certainly than one can determine a child’s father. Thus the Qur’an always refers to Jesus as the son of Mary; and never refers to Jesus as the son of God or the son of Joseph.
However, the Torah does trace descent through the male line and not the female line. Thus all male descendants of Aaron, the first Cohen-priest are Cohanim, who can pass on to their sons the Cohan status. The son of a Ben Cohen-priest is himself automatically a Cohen; but the son of a Bat Cohen is not a priest.
Male descent has been the usual way status was inherited in the western world for the last 4,000 years. So why was the status of Jewishness so exceptional?
The Zohar (I 122b; Pritzker edition, Matt tr) says: “Since Abraham and Sarah did not embrace or cling to this site (the sitra achra), Sarah attained supernal life for herself, her husband, and her descendants after her. “
What does this mean? Although Jews always think of Abraham as the first Jew, Abraham himself was not born Jewish. Nor was he the first convert to Judaism, since in his youth, no Jewish community existed for him to join.
After Sarah made Abraham Jewish by attaining supernal life for herself and for Abraham, then both of them, especially Sarah, created a Jewish community by influencing non-Jews to become Jewish. (see Rashi on Genesis 12:5)
Sarah was the first Jew, and when: “Sarah attained supernal life for herself, her husband, and her (biological) descendants after her” it means that Sarah attained the energy for the sanctification of Jewishness not only for herself, but also for her husband, and for all her descendants (both male and female) after her.
The proof of this according to the Zohar, comes from the prophet Isaiah: “Look to the rock (Abraham) from which you were hewn, and to the quarry (Sarah) from which you were dug.” (51:1) The very next verse explains the metaphor: “Look to Abraham your father and to Sarah who birthed you.” (51:2)
The sculptor hews the outside off the material, to reveal the inner art form; but first the quarryman digs the material out of the earth (womb) so it can be made into a jewel or a work of art.
Thus, the womb of every Jewish mother has the power to produce a Jewish child, which is not possible even for the most pious male rabbi in the world.
This is why God commanded Abraham to listen to Sarah’s words, when she told him to expel Hagar with her son Ishmael from her household, and Ishmael, Abraham’s son but not Sarah’s, would also become a great non-Jewish nation. (Geneses 21:10-13)
How Jewish Sarah’s children will be depends on the art and skill of all the Jews, both male and female, who sculpt the child throughout his or her life. Michelangelo could sculpt a David; but he could not make the marble slab that was dug from mother earth.
Supernal life is not only a long life of personal holiness and purity of heart; on its highest level it is a life that reaches out to inspire the lives of others, especially non-Jews, to enter into higher and higher realms of Jewishness.
This is why no other person in the Bible is described as living multiple lives, ‘Khayay’ as in “Khayay Sarah” Sarah’s Lives (Genesis 23:1). Sarah’s life of Jewishness gave birth to her loyal and faithful husband Abraham’s Jewishness (monotheism by itself does not create Jewishness).
Sarah’s supernal energy also gave all her female descendants the power to create Jewish lives in their own womb; and often to create Jewish lives in their own homes, for their Goyish husbands to become part of a Jewish family and a Jewish community.