The Holy One, Blessed is He, spoke to all other righteous women through an angel, but to Sarah He spoke through Divine communication (Lekach Tov, Bereishit 23:1).
All of Egypt was irradiated with her beauty. Rabbi Yitzhak said: "Some very righteous and prominent women are blessed with beauty that resembles that of Eve, but Sarah was very beautiful (Genesis 12:14), even more than the image of Ev" (Bereishit Rabbah 40:5).
All the years of Sarah’s life a cloud, signifying the Divine Presence, hovered over her tent; the flaps of the tent were open from both sides; her dough was blessed; and a lamp burned in her abode from one Sabbath eve to the next. When Sarah died, all these ceased, but when Rebecca came, they all returned (Bereishit Rabbah 60:16).
Sarah was first called Sarai - in Hebrew, "my princess.” As her life evolved, and through her partnership with Abraham, she earned a new appellation, Sarah - no longer "my princess” but "princess” to the whole world. Indeed, if Abraham earned the sobriquet "our father,” then Sarah most certainly merited the parallel title "our mother.”
Although society changes and definitions of words as well as people’s roles acquire different meanings and implications, Sarah qua Sarah continues to endure as a model for all Jewish women. This was a person totally dedicated to her husband Abraham not because he was her husband, but because they viewed their lifework as a "team effort,” a career of mutual devotion, dedication, and loyalty to the future of their family and to their people.
That she was beautiful - inwardly and outwardly - is Biblically explicated. That she was fiercely loyal and determined to protect her domain and her rightful place by Abraham’s side, despite that most famous couple’s inability to procreate, is also vividly expressed in the Scriptural text. That she was less than gracious to Hagar, with whom Abraham cohabits, and to Ishmael, their offspring, is eminently understandable in the context of her designated role as matriarch of the Jewish people. Filial preferences did take place in the Biblical world. Although rescued thousands of years later in the fiction of Herman Melville by another great Jewish matriarch, Rachel, Ishmael was never seen as the rightful heir of Abraham because he was not the progeny of Sarah.
All this is reconciled through the amazing revelation that Sarah would give birth to a son at the age of 90. Abraham is a mere 100, and his laughter at his and Sarah’s Divine fortune is impressed upon our people’s heritage through the career of Isaac, whose Hebraic name means "laughter.” Sarah seems, in the Divine scheme, to have the "last laugh,” but considering the trials of her existence, and her anxieties concerning Isaac’s destiny, her resultant amusement is, most surely at this mature age, sardonic.