The name of fifth section of the Book of Genesis is taken from its first words, "The Life of Sarah" (Chayei Sarah in Hebrew), and begins with Sarah's death and burial. We then follow Abraham's servant, Eliezer, as he betroths Abraham's grandniece Rebecca to Abraham's son Isaac. This account is followed by that of Isaac and Rebecca's marriage and the closing phases of Abraham's life: his remarriage to Hagar, his death, and his son Ishmael's departure from his family and its Divine mission.
Inasmuch as Chayei Sarah means "the life of Sarah," it follows that it is Sarah who is the protagonist, the heroine of this parsha. At first glance, this seems baffling, since Sarah's life came to an end in the previous parsha and parshat Chayei Sarah seems to emphasize the finality of her death: Abraham must arrange for her burial, he must find a wife for his son to succeed Sarah as the matriarch of his household, and he marries Hagar to have a wife in Sarah's stead. Finally, the parsha closes by recording the genealogy of Ishmael, whom Sarah had expelled from her home.
But in truth, the episodes of this parsha demonstrate how Sarah's life did not end with her death. Rather, the influence of the values and ideals that she worked toward throughout her lifetime continued after her death.
Abraham was the trailblazer in disseminating the awareness of G-d in the world, as we have seen. But in order to spread the message of monotheism and morality to an idolatrous, immoral world, he had to focus on humanity's great potential, deliberately turning a blind eye to its imperfections. Abraham personified the attribute of chesed: giving endlessly and indiscriminately, accepting everyone with unqualified love, seeing them as the best they can be regardless of who they are now.
Sarah helped Abraham spread his message among the world's women with the same undiscriminating eye he used toward the world's men. When Isaac was born, however, and they were entrusted with raising a child who would have the strength to carry on their Divine mission, she realized that this universalism would have to be tempered by a discerning particularism.
Abraham could afford to be unconditionally accepting as long as it was just he and his wife interacting with their audience. But once their mission of disseminating Divine consciousness was to be passed on to a family, and eventually to a whole people, steps had to be taken to ensure that this message be passed on with uncompromising purity, direction, and force.
Thus, Sarah, the mother entrusted with nurturing Abraham's successor, undertook to insulate the family from deleterious influences. As soon as Ishmael became just such an influence, and Hagar proved unwilling or unable to check his untoward behavior, Sarah insisted that they both be sent away. Abraham was troubled by this, but G-d settled the matter, instructing Abraham to follow Sarah's advice. Abraham's universalism is appropriate in its place, but out of place, it becomes counterproductive. A family or a people, like any living organism, must have well-defined borders; if not, the health and integrity of the entire organism are compromised.
Sarah's particularism was thus the next stage in the process of the creation of the Jewish people. Abraham initiated the process by reviving the world's awareness of G-d; Sarah ensured the continuation of this process by defining the parameters of the relationship between Abraham's heirs and the world they were charged to mentor.
The lesson of parshat Chayei Sarah, then, is that universalism must operate hand-in-hand with particularism. We are all Abrahams, charged with the mission of spreading Divine consciousness to the whole world; as such, we must always strive to view humanity in the best possible light, and each individual as a precious child of G-d who deserves our unconditional love and the best we can give, both materially and spiritually. But concomitantly, we must also all be Sarahs, cherishing the integrity of the bearers of the Divine message and acutely aware of the fact that G-d has entrusted His mission to us -- that we bear the message and that the world is our audience.
--Excerpt from the Kehot Chumash - Synagogue Edition