Parashat Chayei Sarah marks the transition of the matriarchy from Sarah to Rivkah. A great deal of the narrative is devoted to the death and burial of Sarah on the one hand, and the search for a wife for Yitzchak on the other. Rabbi Yosef Dov Soloveitchik zt”l once noted that with the death of Sarah, “(Avraham) walks off the covenantal stage.” Despite his relative longevity, after Sarah’s passing Avraham seems to “disappear:” He ceases to be a major player, and the mantle of leadership passes to Yitzchak — and Rivkah. Apparently, the partnership between Avraham and Sarah was such that the death of one causes the focus to shift away from the other. Theirs was a complete, total partnership, and Avraham was keenly aware of the nature and importance of this partnership. Therefore, as soon as the burial and mourning period ended, he set out to find a woman who could partner with Yitzchak in the same way.
The centrality of this partnership in the mission Avraham had taken upon himself, the mission that Yitzchak would soon inherit, is clear from the very outset: In Parashat Lech Lecha, we are told that when Avraham and Sarah headed toward the Land of Canaan, they brought with them “the nefesh they had made in Charan.” This is understood as a reference to their followers, to the people whom they had converted to monotheism. Rashi explains:
רש"י בראשית פרק יב:ה
… אברהם מגייר את האנשים, ושרה מגיירת הנשים…
…Avraham converted the men and Sarah converted the women. (Rashi, Bereishit 12:5)
Avraham and Sarah shared their mission – as equals, each of them working in their own sphere of influence. This observation gives us some insight into the spiritual greatness of the patriarchs and the matriarchs. In his eulogy for Sarah, Avraham explains to the world who she was and what had been lost with her passing. Sarah was more than just the woman who prepared food for Avraham’s guests; she took a proactive role in educating and inspiring other women.
Of all her students, one stands out in particular: Hagar. When she is introduced in Chapter 16 of Bereishit, Hagar is described only as Sarah’s Egyptian servant, but midrashic literature (cited by Rashi) provides some biographical information:
בראשית רבה (וילנא) פרשת לך לך פרשה מה סימן א
אמר ר"ש בן יוחאי הגר בתו של פרעה היתה וכיון שראה פרעה מעשים שנעשו לשרה בביתו נטל בתו ונתנה לו, אמר מוטב שתהא בתי שפחה בבית זה, ולא גבירה בבית אחר.
Rabbi Shimon ben Yohai taught: Hagar was Pharaoh’s daughter. When Pharaoh saw what was done on Sarah’s behalf in his house, he took his daughter and gave her to [Avraham], saying, “Better that my daughter should be a handmaid in this house than a mistress in another house.” (Bereishit Rabbah 45:1) 
When it became apparent to Sarah that she would be unable to bear children, she sought an appropriate partner for Avraham, one with the most illustrious lineage that she could find. A lesser woman than Sarah might have been afraid to bring in such “competition,” but Sarah felt that if Avraham was to have a child, that child must be the greatest child possible. In an act of complete self-sacrifice, Sarah invites her protégé, the erstwhile Egyptian princess, to bear a child for Avraham.
בראשית רבה (וילנא) פרשת לך לך פרשה מה סימן ג
ותקח שרי אשת אברם את הגר המצרית שפחתה, לקחתה בדברים אמרה לה אשריך שאת מדבקת לגוף הקדוש הזה.
“Sarai, Avram’s wife, took Hagar the Egyptian...” (Bereishit 16:3). She took [persuaded] her with words: “Fortunate are you to be united with so holy a man.” (Bereishit Rabbah 45:3)
Hagar, who had been Sarah’s primary disciple, became pregnant. She concluded from this that God now favored her, and not Sarah, and that Sarah was an unworthy partner for Avraham. As a result, she began to conduct herself as the head of the household.
בראשית רבה (וילנא) פרשת לך לך פרשה מה סימן ד
…והיתה הגר אומרת להם שרי גבירתי אין סיתרה כגלויה נראית צדקת ואינה צדקת אילו היתה צדקת ראו כמה שנים שלא נתעברה ואני בלילה אחד נתעברתי ...
…Hagar would say, “My mistress Sarah is not inwardly what she is outwardly; she appears to be a righteous woman, but she is not. She has not merited to conceive all these years, whereas I conceived in one night.” … (Bereishit Rabbah 45:4)
It is not difficult to understand, or perhaps even sympathize with Hagar. She had been born into the aristocracy, but a serendipitous event led her away from her father’s pagan world. Perhaps Avraham’s genius captivated her, and she came to believe that it was better for her to serve in his house than to rule Egypt. But now, after many years of service, the opportunity to rule in Avraham’s house unexpectedly landed in her lap, as it were. She believed that she had received a Divine sign that she, who was born to be queen, would, indeed be the queen — of Avraham’s nascent movement.
Hagar’s mistake was in assuming that Avraham alone led the people, that he alone was a spiritual giant. She failed to recognize that it was a partnership, the combination of Avraham and Sarah, that was the basis for the great spiritual movement she herself had become a part of.
Sarah understood very well what Hagar had missed, and Sarah responded - not out of selfishness, not out of jealousy. Sarah understood that she and Avraham were partners and equals. The moment Hagar overstepped the boundaries of her role, Sarah made those boundaries very clear, and insisted that Avraham do the same. Although Hagar was offended, even aggrieved, her pain was not the result of some petty squabble with her “boss;” Hagar was crestfallen when she was made to understand that she would not be replacing Sarah as Avraham’s partner. Later, when Hagar’s son Yishmael exhibited the same desire to usurp Yitzchak’s position as heir to Avraham’s spiritual legacy, Sarah informed Avraham that it was time to send Hagar and Yishmael away. Avraham was upset, conflicted, and God Himself had to help Avraham put things into perspective:
בראשית פרק כא, יב-יג
וַיֹּ֨אמֶר אֱלֹהִ֜ים אֶל־אַבְרָהָ֗ם אַל־יֵרַ֤ע בְּעֵינֶ֙יךָ֙ עַל־הַנַּ֣עַר וְעַל־אֲמָתֶ֔ךָ כֹּל֩ אֲשֶׁ֨ר תֹּאמַ֥ר אֵלֶ֛יךָ שָׂרָ֖ה שְׁמַ֣ע בְּקֹלָ֑הּ כִּ֣י בְיִצְחָ֔ק יִקָּרֵ֥א לְךָ֖ זָֽרַע:
But God said to Avraham, 'Do not be troubled because of the boy and your slave. Do everything that Sarah tells you, for it is through Yitzchak that you will gain posterity. (Bereishit 21:12)
To make this point even stronger, Rashi explains that Sarah’s prophetic abilities surpassed Avraham’s; her decision to banish Hagar was the result of superior prophetic perception. And yet, they were partners; there could be no replacements, neither for Sarah nor for Avraham. Without Sarah, there is no Avraham. The covenantal community requires two leaders, a man and a woman, Avraham and Sarah.
Our sages find other intimations of Sarah’s greatness in the text: Commenting on a verse at the end of our parashah, Rashi records an oral tradition preserved in the Midrash: 
בראשית פרק כד, סז
וַיְבִאֶ֣הָ יִצְחָ֗ק הָאֹ֙הֱלָה֙ שָׂרָ֣ה אִמּ֔וֹ וַיִּקַּ֧ח אֶת־רִבְקָ֛ה וַתְּהִי־ל֥וֹ לְאִשָּׁ֖ה וַיֶּאֱהָבֶ֑הָ וַיִּנָּחֵ֥ם יִצְחָ֖ק אַחֲרֵ֥י אִמּֽוֹ:
Yitzchak brought [Rivkah] to the tent of his mother Sarah. He took Rivkah [in matrimony] and she became a wife for him; and he loved her, and he was consoled after his mother. (Ibid. 24:67)
רש"י בראשית פרק כד:סז
האהלה שרה אמו: ויביאה האהלה ונעשית דוגמת שרה אמו, כלומר והרי היא שרה אמו, שכל זמן ששרה קיימת היה נר דלוק מערב שבת לערב שבת, וברכה מצויה בעיסה, וענן קשור על האהל, ומשמתה פסקו, וכשבאת רבקה חזרו.
“To the tent of his mother, Sarah:” She became the image of his mother Sarah, as if to say, ‘Behold, she became Sarah.” As long as Sarah was alive, the candle [in her tent] remained lit from one Shabbat Eve to the next, her dough was blessed, and a cloud was tied to her tent. When Sarah died, all these things ceased, and when Rivkah entered the tent, all these phenomena returned. (Rashi, Bereishit 24:67)
The reference to “a cloud tied to her tent” is a very particular, and also a very uncommon image which appears in midrashic literature only very rarely. Of particular interest is the occurrence involving Avraham and Yitzchak: As Avraham headed toward the Akeidah, he lifted his gaze and saw something that was at once both physical and spiritual: He was able to identify the place he sought because he saw a mountain with a peculiar cloud “tied” to its summit. Yitzchak shared this vision; the other young men who accompanied them did not.
בראשית פרק כב, ד-ה
בַּיּ֣וֹם הַשְּׁלִישִׁ֗י וַיִּשָּׂ֨א אַבְרָהָ֧ם אֶת־עֵינָ֛יו וַיַּ֥רְא אֶת־הַמָּק֖וֹם מֵרָחֹֽק: וַיֹּ֨אמֶר אַבְרָהָ֜ם אֶל־נְעָרָ֗יו שְׁבוּ־לָכֶ֥ם פֹּה֙ עִֽם־הַחֲמ֔וֹר וַאֲנִ֣י וְהַנַּ֔עַר נֵלְכָ֖ה עַד־כֹּ֑ה וְנִֽשְׁתַּחֲוֶ֖ה וְנָשׁוּ֥בָה אֲלֵיכֶֽם:
On the third day Avraham lifted up his eyes and saw the place from afar. And Avraham said to his young men, ‘Stay here with the donkey; and I and the lad will go yonder and worship, and come back to you. (Bereishit 22:4-5)
מדרש רבה בראשית פרשה נו סימן א,ב
ביום השלישי וירא את המקום מרחוק מה ראה ראה ענן קשור בהר אמר דומה שאותו מקום שאמר לי הקב״ה להקריב את בני שם:
אמר ליצחק בני רואה את מה שאני רואה א״ל הין אמר לשני נעריו רואים אתם מה שאני רואה אמרו לו לאו אמר הואיל וחמור אינו רואה ואתם אין אתם רואים שבו לכם פה עם החמור…
“On the third day…he saw the place from afar.” What did he see? He saw a cloud tied the mountain, and said: ‘It appears that that is the place where the Holy One, blessed be He, told me to sacrifice my son.’ He then said to him [Yitzchak]: ‘Yitzchak, my son, do you see what I see?’ ‘Yes,’ he replied. [Avraham] then said to his two servants: ‘Do you see what I see?’ ‘No,’ they answered. “Since you do not see it, ‘Stay here with the donkey…’ (Bereishit Rabbah 56:1–2)
The two young servants saw only the mountain, the physical reality devoid of the spiritual component expressed by the cloud. Therefore, Avraham instructed them to remain with the chamor, the donkey. As we noted in Parashat Vayeira, the root of this word is chomer, denoting physicality. Avraham and Yitzchak are able to see both the physical and metaphysical, but the others are limited to the physical plane. They do not see the cloud; they are, therefore, unworthy of continuing the spiritual journey that Avraham and Yitzchak share.
Interestingly, Avraham is described in the Midrash as one of three people who rides on a chamor; the other two are Moshe and the Messiah (Mashiach).
The prophet Zecharyah describes Mashiach as a poor man riding on a donkey.Citing this verse, the Gemara teaches that there are two possible scenarios for the final redemption and the onset of the Messianic Age:
תלמוד בבלי מסכת סנהדרין דף צח עמוד א
אָמַר רַבִּי אֲלֶכְּסַנְדְּרָאִי, רַבִּי יְהוֹשֻׁעַ בֶּן לֵוִי רָמִי, כְּתִיב, [דניאל ז] "וַאֲרוּ עִם עֲנָנֵי שְׁמַיָּא כְּבַר אֱנָשׁ אָתֵהּ", וּכְתִיב, [זכריה ט] "עָנִי וְרֹכֵב עַל חֲמוֹר". זָכוּ - "עִם עֲנָנֵי שְׁמַיָּא", לֹא זָכוּ "עָנִי וְרֹכֵב עַל חֲמוֹר".
Rabbi Alexanderi taught: Rabbi Yehoshua ben Levi contrasted two verses: It is written [Daniel 7:13], “Behold, one resembling a son of man came with the clouds of heaven,” and [in Zecharyah 9:9] it is written, “[Behold, your king will come to you] lowly, and riding upon a donkey.” If [the Jewish people] are meritorious, [Mashiach will come] with the clouds of Heaven; if not, [he will be] lowly and riding upon a donkey. (Talmud Bavli Sanhedrin 98a)
The denouement of history is in our hands. The Mashiach will be revealed in clouds of glory if we are worthy; if we are unworthy, our redemption will be of a far less exalted nature. If we are deserving, the clouds will be revealed sooner; if not, the redemption will take longer, and the process will be slow and plodding - but the redemption will surely come. And just as the clouds are an image that is laden with meaning, representing man’s ability to recognize and connect to the metaphysical plane, so, too, the image of the Messiah as a poor man riding on his donkey is no mere literary device: According to mystical sources, this metaphor holds the key to the redemption itself: The Zohar explains that the role of Mashiach is to ride on the chamor, to subdue the physical.
In Jewish thought, there is no ideological tension between the physical world and the spiritual world. The physical world was created for our benefit, and we are entrusted with its care and proper use. The physical world is a means to an end; we are charged with elevating and perfecting our physical selves and the physical world around us by utilizing them in spiritual contexts. So many individuals, movements, philosophies and nations have made (and continue to make) the tragic error of worshipping the physical as an end unto itself. In this vein, Jewish mysticism describes the Messiah as one who rides on top of the chamor, subdues the physical, and ushers in an age of enlightenment in which all of humanity is able to rise up and connect with the spiritual plane.
This, then, is the greatness that Avraham displayed throughout his life: He knew how to master the physical world around him. He understood that man-made idols are meaningless. He was willing to commit himself and his offspring to the covenant of circumcision in order to perfect his body and to symbolize the goal of controlling his physical nature. He and Yitzchak were able to see the cloud, to transcend the shackles of the physical plane, and ascend the mountain. He and Yitzchak were uniquely capable of overcoming their own physical limitations as they willingly submitted to the test of the Akeidah.
The matriarchs, too, shared this unique vision. Sarah, and then Rivkah, had “a cloud tied to her tent” – the same cloud that was “tied” to the place of the Akeidah, the holiest place in the world according to Jewish tradition. Despite the fact that they lived in the physical world, they were connected to the spiritual world.
Avraham and Sarah, Yitzchak and Rivkah were equals — all of them, spiritual giants. However, Avraham saw the cloud only when he was on the way to offer his beloved son as an offering. Only when he was willing to surrender everything he loved to the Almighty did he merit this spiritual vision. Yitzchak saw the cloud when he prepared to give his life for the service of God. And yet, we are told, this vision was a constant guest in the tent of Sarah, and then Rivkah. The spiritual apex Avraham and Yitzchak achieved at the Akeidah was the spiritual norm that Sarah and Rivkah experienced (and shared with others) in their personal lives, in their tents, each and every day.
How did Sarah achieve this exalted level of spirituality? We are told that Sarah died at the age of 127. Rashi, drawing on the Midrash, explains that when she was one hundred years old, she was like a twenty-year-old regarding sin: Until twenty years of age, we are not held responsible for our actions. Thus, we are all completely free of sin at the age of twenty. At the age of one hundred, Sarah was equally clean of sin.
When she was twenty, the Midrash continues, she was as beautiful as a seven-year-old. Here, the Midrash is somewhat difficult to understand; in fact, we might have reversed the two analogies, comparing her innocence to that of a seven-year-old, and her beauty to that of a twenty year old. Rabbi Shimshon Raphael Hirsch explains that in truth, a seven-year-old is quite beautiful — perhaps not in a sexual or sensual sense, but with the beauty of a child. We would think that the idea of sinlessness would be more appropriate for a seven-year-old than for a twenty-year-old, but Rabbi Hirsch points out that a seven-year-old lacks the opportunity and capability to sin. Sarah’s purity, then was not that of a seven-year-old child who has neither the inclination nor occasion to sin, but rather of the twenty-year-old who makes conscious choices and refuses to sin.
Rabbi Soloveitchik zt”l explained that the greatness of Sarah and her role within the covenantal community may be culled from the words of Rashi: She was one hundred, she was twenty, she was seven: Whereas most people pass from one stage of their lives to the next, leaving the previous stage behind and taking with them nothing more than fond memories, Sarah retained the essence of each stage of her life even after she moved on to the next one. Each one of these ages — one hundred, twenty, seven — has unique qualities. A seven-year-old has innocence; a twenty-year-old has strength; a hundred-year-old has wisdom. The secret of Sarah’s greatness was that throughout her entire life she was one hundred and twenty and seven. Rashi explains the words, “the years of the life of Sarah:” All were equally good. At every point in her life, Sarah remained the same. She was always as innocent as a seven-year-old, with the strength, determination, and idealism of a twenty-year-old, and the wisdom of a one hundred-year-old.
While each of these traits is certainly desirable, their importance to the religious character is even greater: Innocence is a quality necessary for prayer; in order for a person to pray, he or she must feel that God is really listening. The cynicism that so many of us accrue as we move through life eats away at this innocence, and we lose the ability to stand before God and verbalize our innermost thoughts, fears, and aspirations. A child, on the other hand, is not weighed down by cynicism and still possesses the ability to relate directly and honestly to a loving parent. When we pray, we should feel that God is our Father in Heaven and we are His children; Sarah never lost that innocence.
The greatness of a twenty-year-old is physical strength and idealism. A twenty-year-old feels that he or she can change the world, that anything is possible. There are no limits, no rules - only potential. Twenty-year olds feel that they are not limited by the mistakes and failings of the previous generation. They believe they can build something greater. This is how Sarah retained the strength of a twenty-year-old — by always remaining idealistic, never feeling limited.
A one-hundred-year-old possesses wisdom, born of the perspective that only experience can give. Great sages are almost always older people whose skills have not diminished over the years. Quite the opposite: they possess insight and sensitivity that transcends “book knowledge.” Sarah always had this wisdom. Similarly, even at a tender age Rivkah was able to transcend her station and relate to others as a person far beyond her years.
Sarah was always one hundred, and twenty, and seven. Throughout her life she possessed all these skills. This is the greatness of Sarah, the greatness which made her our first matriarch - and the perfect match for Avraham.