The quintessential image of Jewish home and motherhood is that of a woman blessing the Shabbat candles. The familiar ritual has existed since time immemorial, right? Wrong. In fact, it was only 900 years ago that, after much debate, lighting a lamp for Shabbat came to be defined as a mitzva—one with its own blessing and one that Jewish women took upon themselves.

Because there is no such commandment in the Torah, most rabbis before 1000 C.E. maintained that lighting a Shabbat lamp was merely a task women did since they were home and men were in synagogue on Friday afternoon. It was important only because without a lit lamp the family would sit in the dark for the Friday night meal. And while the Talmud meticulously details the kind of oil and wick that best keeps the lamp burning, there is no mention of a special ritual for lighting it.

Rashi (1040-1105), as the great French Talmudist Rabbi Shlomo Yitzhaki is called, took a different view. In his commentary on Tractate Shabbat (23b), he states, “By observing the mitzvot of kindling a lamp on Shabbat and Hanukka, one brings the light of Torah into the world.”

Yet even if a community accepted that kindling a light was a mitzva, should a blessing accompany it? And if so, which one? With none designated in the Talmud, and halakha forbidding the creation of a new blessing, medieval Sefardic women lit their Shabbat lamps without a blessing.

However, during the 11th century, Ashkenazic women had greater religious status and autonomy than those in Sefarad, so much so that they began to fulfill mitzvot men were obligated to perform, such as blowing the shofar and wearing tefilin and tzitzit. According to Machzor Vitry, a compendium of laws and customs collected by Rashi’s students, women took these commandments upon themselves and recited blessings as well, in the same way that women today have instituted new rituals like bat mitzva, tefila groups and minyans, and become rabbis and cantors.

Rashi clearly accepted kindling the Shabbat lamp as a mitzva, one that women, as well as men, were obligated to perform. Thus it seems logical that if women made a blessing when they performed mitzvot from which they were exempt, surely they must say one if they perform a mitzva for which they are obligated. And indeed, Rashi’s grandson, Rabbeinu Tam, declared that lighting the Shabbat lamp required a blessing.

But what prayer should be said? The solution was to take the blessing for lighting the Hanukka menora, which was in the Talmud, and substitute “Shabbat” for “Hanukka.” As astonishing as it may seem, the Hanukka blessing is 1,000 years older than the Shabbat blessing.

We know of this new blessing because we have a responsum by Rashi’s granddaughter, Hannah, describing the ritual her mother performed. She explained that in Rashi’s house the woman first lit the Shabbat lamp and then recited the benediction, her words the same ones we say today. Rabbeinu Tam’s decision and his sister Hannah’s responsum were so authoritative that within a hundred years, even women in Sefarad were saying this blessing.

Today, when women (and men) light Shabbat candles, they never imagine the ritual doesn’t come from Sinai. And who knows? Maybe in another 900 years Jews will assume girls have always had a bat mitzva, or that there have always been women rabbis. As for our generation, it seems we are only following in the footsteps of the women of Rashi’s time.

Maggie Anton (www.rashisdaughters.com) is the author of the novel Rashi’s Daughters: Book One– Joheved (Banot Press).