Who ‘Fixed’ the Jewish Calendar?

A glimpse at the Jewish year across time and space

These moveable wheels known as "volvelles" appear in an 18th century Germany manuscript called Sefer Evronot. They allowed readers to keep track of the Jewish calendar. From the National Library of Israel collection

In ancient Israel, there was no fixed calendar.

New months were only declared by the rabbinic court after witnesses came to testify that they had seen the new moon.

In this way, each month essentially reflected a partnership between the Jewish people who declared the moon and God who mandated that certain days be sacred, dedicated to sacrifices and celebration.

Using astronomical calculations instead of witnesses, a sage by the name of Hillel the Second boldly established the set Jewish calendar in the 4th century, a few centuries after the destruction of the Second Temple in Jerusalem.

This is the calendar still used by Jews across the world until today!

Check out the clip below for a glimpse at a 900 year-old Jewish calendar and other rare treasures from the National Library of Israel’s world-leading collection, as well as some insights into how the Jewish year was recorded and remembered across the world over the centuries.

The film is part of “A Look at the Jewish Year,” a series presented by the National Library of Israel in collaboration with the Pardes Institute of Jewish Studies, which provides insights into the Jewish calendar and holidays through the lens of the National Library of Israel’s world-leading collection of Jewish manuscripts, books, printed materials and more.

The project also includes source sheets with questions and links to additional materials that can be used to help lead group discussions and activities or enriched personal reflection.

The Worm That Built Solomon’s Temple

Did a mysterious little creature, the enigmatic "Shamir", really help build the First Temple?


The Book of Kings contains a precise description of the building of the First Temple: its dimensions, the cedar and cypress beams that covered the walls, the gilded ornaments and carvings, and the two cherubim that stood wing to wing above the Ark of the Covenant. It also includes this puzzling verse: “And the house, when it was in building, was built of stone finished at the quarry, and there was neither hammer nor axe (nor) any tool of iron heard in the house, while it was in building.” (1 Kings 6:7)

How could it be that no hammers, chisels or iron tools were used to carve the stones of the Temple, while the Bible also states that the stones were hewn? The Jewish sages offer a simple answer:  the stones were prepared in another location and transported from there to the construction site at the Temple Mount. The Book of Kings even brings support for this explanation: “And the king commanded, and they quarried great stones, heavy stones, to lay the foundation of the house (with) hewn stone.” (1 Kings 5:31).

But our interest here is the alternative explanation, appearing in Rabbinic literature, according to which the stones were hewn with the help of something called Shamir. The obscure Shamir appears in the Bible itself, though not in the Book of Kings. In Ezekiel (3:9) it is written that Shamir is “stronger than flint.” The Hebrew text of Jeremiah 17:1 also makes mention of Shamir, though English versions have translated the word as “flint” or “diamond”: “The sin of Judah is written with a pen of iron, with a diamond [Shamir] point, engraved on the tablet of their heart and on the horns of your altars.” These passages clearly suggest that Shamir is a hard material of some kind.

The Talmud provides additional information about the mysterious Shamir. For example, in Tractate Avot, Shamir is mentioned as one of the ten things created on the “Sabbath eve,” before the completion of the act of Creation. The substances created in that moment were somewhat enigmatic in nature, including the Shamir which had the power to hew stones. Tractate Sotah (48b) explains that the Shamir was used to engrave the stones inserted into the Priestly breastplate (Hoshen), which were cut “like a fig which splits open in summer.” It also says there that because nothing could withstand the Shamir’s strength, it is stored in tufts of wool in a lead box filled with barley bran.

Model of the Temple from a book of photographs of Temple models donated to the National Library of Israel in the 1930s

The Talmud, Tractate Gittin (68a) contains the most detailed legend surrounding the Shamir. According to the story, King Solomon asked his advisors how the stones for the Temple could be prepared without the use of an axe or chisel, as it was inappropriate to use tools of bloodshed and war to construct such a building. They told him of the miraculous Shamir but did not know where to find it. The king then summoned forth spirits and demons, but these were also unable to say where it might be found. They did, however, suggest that Solomon consult their lord, Asmodeus, king of demons, who might know the answer. King Solomon sent his general, Benayahu son of Yehoyada, who subdued Asmodeus and brought him to the king’s palace. Asmodeus (or Ashmedai) revealed to Solomon that the Shamir was in the possession of the Lord of the Sea, guarded by a certain bird, a woodcock according to most English versions of the story. Solomon quickly sent off another of his servants who prevailed over the woodcock and managed to steal the Shamir away. From here the story continues, with further twists and turns. You can read a version of the legend in Louis Ginzberg’s classic, “The Legends of the Jews”, as well as a Hebrew version which is available online here (in Kol Agadot Yisrael, ed. Israel Benjamin Levner, Tushiya Publishing).

“…and He named it ‘Shamir’, and placed it to rest in safekeeping, in a place unknown to humans“, a page from the legend of King Solomon and Asmodeus, Kol Agadot Yisrael, I. B. Levner

In Rashi’s commentary to the legend, he deduced that the woodcock was in fact a hoopoe (duchifat in Hebrew, דוכיפת), which became a popular fixture in the legends of King Solomon. But more to the point, he suggested that the Shamir was not a stone or other inanimate object at all, as can be assumed from some of the versions of the legend, but was in fact a living creature—a worm. The source of Rashi’s explanation is unclear, but the phrase “Shamir worm” was born and even made its way into the writings of Mendele Mocher Sforim (Sholem Yankev Abramovic, 1836–1917), who mentions the Shamir as one of the wondrous creatures that Benjamin the Third sets out to find in his travels.

Illustration for the legend of King Solomon and Asmodeus. Illustrator: J. Apter. From the book Shlomo Hamelekh – Agadah Ketuva Beyad, [Hebrew] H.N. Bialik, Frankfurt, 1923

The religious commentators do not agree on whether the Shamir was a living creature or a kind of stone with miraculous powers. On the other hand, based on the Talmud (Tractate Sotah 48b), they determined that after the Temple was destroyed, the Shamir was obliterated from the world. However, about two years ago, a team of researchers in the Philippines discovered a worm capable of eating through limestone. While limestone is a relatively soft form of rock, nevertheless, the existence of a stone-carving worm might not be such an unrealistic notion after all…

The Feminist Revival of Tu B’Av, the Jewish Festival of Love

Did an Orthodox girls' movement and its legendary founder revive an ancient and obscure holiday in the forests of Poland?

"...the holiday that belongs to us, to young Jewish women.” (Photo: The Yad Izhak Ben Zvi Archive, part of the National Library of Israel Digital Collection)

Do a quick Google search on Tu B’Av, and two sorts of material will appear. The first describes a festival dating back to late antiquity, in which, according to Mishnah Ta’anit 4:8, “On these days [the 15th of Av] the daughters of Jerusalem would go out in borrowed white garments in order not to shame anyone who had none…  The daughters of Jerusalem would come out and dance in the vineyard. What would they say? Young man, lift up your eyes and see what you choose for yourself…”

Girls dancing on Tu B’Av in Hadera, early 20th century. From the Khan Hadera Archive and Museum (Photo: Sonia Kolodany / Photo Sonia / CC BY 2.5)

Along with this ancient matchmaking festival, we might also learn of the revival of Tu B’Av in modern Israel, as a Jewish Valentine’s Day, or festival of love. The Orthodox world, in Israel and beyond, has also taken up this day as a “Global Day of Shidduchim,” in which great rabbis pray, without charge, for unmarried men and women to find their mates.

Yet Tu B’Av, it turns out, may have been first revived in the modern period neither by modern Zionists celebrating romance nor by Orthodox organizations praying for “shidduchim.”

Bais Yaakov

Now generally associated with perhaps less-than-progressive ultra-Orthodox educations for girls, the Bais Yaakov movement was actually quite radical in its early years.

In 1917, a dressmaker with an eighth-grade education named Sarah Schenirer opened a girls’ school in Kraków, hoping to stem the tide of Orthodox girls who were abandoning tradition.

Sarah Schenirer. From Collected Writings, the National Library of Israel collection

By the 1930s, the movement had branches on three continents and dozens of schools, not to mention vocational training institutes, a chain of colonies and summer camps, three teachers’ seminaries, a monthly literary journal and other periodicals, its own publishing houses, a youth movement and much more. The character of the movement changed dramatically after the Holocaust, yet recently the Bais Yaakov Project was founded to preserve and share this fascinating early history.


The women’s holiday

Online as part of the Bais Yaakov Project archives, a 1926 issue of The Bais Yaakov Journal reports local celebrations of Tu B’Av throughout Poland that year. The newspaper describes the numerous correspondents who wrote in to the office of the Bnos (the youth movement associated with the Agudah and Bais Yaakov) to report on how they had celebrated the day and to express “the outpouring of joy awakened by the revival of this traditional historical women’s holiday.”

Beis Yaakov activities in Rabka (near Skawa), 1929. From Collected Writings, the National Library of Israel collection

The fact that this was not a one-time occurrence in 1926 but a regular feature of Bnos and Bais Yaakov life is evident from other writings, including by Sarah Schenirer, detailing how this old-new holiday might be celebrated, and clarifying its meaning for the Bais Yaakov movement. One participant in a Tu B’Av ritual led by Sarah Schenirer herself provided a rich description of the 1932 celebration in the woods of Skawa, a village thirty miles south of Krakow where the seminary students were spending the last summer before they left for their assigned teaching posts.

The celebration of Tu B’Av, in Hodo Movshowitz’s retelling, involved a moonlight hike in the woods, with 115 students and teachers walking hand-in-hand behind their leader and guide, Sarah Schenirer. After some difficulties, a bonfire is lit, and a student gives a talk, followed by Sarah Schenirer, and then the girls and women rapturously and prayerfully sing and dance, an experience of great mystical meaning.

Beis Yaakov activities near Skawa, 1929. From Collected Writings, the National Library of Israel collection

Tu B’Av was revived in Bais Yaakov as a “traditional historical women’s holiday”; the student who spoke to the group around the bonfire explained its meaning, according to the description, as “the holiday that belongs to us, to young Jewish women.”

The ecstatic dancing was done not before the eyes of prospective mates, as in the Mishnah, but rather, Movshowitz stresses, with no one watching. Tu B’Av was celebrated in Poland by Orthodox Jewish girls and women, alone in the woods with their God, their guide, and each other.


Tu B’Av 1932 in Skawa

Below is the full text of the article, which appeared in a 1932 issue of the Bais Yaakov Journal. It was originally written in Yiddish by Hoda Movshowitz, a teacher in Sokolov, and recently translated into English by Frieda Vizel.

Evening. The sun is about to set. It is already on the other side of the linden trees. (Yes, the trees of Skawa, you will remain in our memory for a long time!) And suddenly it occurs to me: why does the sun hide behind these giant trees every day before it sets? Does it hide behind these enormous trees to prevent people from seeing the last few moments of its day? Maybe it doesn’t want people to see the the misdeeds it has witnessed — is that why it reddens so with shame, and hides its face among the enormous trees?

But I can’t be lost in thought for long. The sound of some exalted mood reaches my ears and rouses me from my speculations.

All the seminary girls are standing in front of the villa, ready for our excursion. We count a hundred and fifteen, and I too am among them.

And so we set out.

Frau Schenirer at the head. One hundred and fifteen of us go step by step, hand in hand, along the path, Frau Schenirer first among us, our guide. Our hearts beating with extraordinary joy, we follow in the steps of our leader and flag-bearer.

The sun is already completely gone. A star-speckled sky is above us. The glow of the moon illuminates our path.

And we walk and walk, but to where? Our great leader is before us, and we follow her lead.

Finally, we reach a forest. It’s pitch dark all around. The trees obstruct even the bright glow of the moon.

Suddenly, the center of our group lights up. “Campfire!” we pass the word from ear to ear. A flash of light, and then it’s pitch dark again. Something over there doesn’t want to burn. The bonfire doesn’t want to start. Our teachers busy themselves with it, to no avail. Some of us despair, but not those in charge of lighting fire, who keep on working with their bundle of twigs. They work with all their energy, lying flat on the ground with their faces close to the spot where a tiny spark still flickers. There they add a bit of their own life force and, finally, they’re successful and the fire catches.

Soon a large fire is burning in the center of our circle, almost like the Jewish fire which we kept burning for so long, deep in our hearts.

It’s quiet. No one dares to speak out loud, to break the silence, to interfere with what we are all feeling. Who? Every one of us! Because we are all experiencing something tremendous—you can see it in our eyes. . .

And then someone does break the silence. Who speaks? One of the students, who begins to give a talk. She speaks and each of her words rings out and is echoed back by the trees.

She speaks of the meaning of the fifteenth day of the month of Av, about the holiday that belongs to us, to young Jewish women. The mood is serious, even sad, as she finishes.

Again a silence lasts for a long time. From time to time we hear the crackle of the burning twigs. And suddenly we hear the voice of Frau Schenirer. All eyes are now focused in one direction, and with great anticipation we listen to the words of our great leader.

Her eyes and the features of her face are sunken in the firelight, but her voice rings out: “And the fire upon the altar shall be kept burning thereby, it shall not go out; and the priest shall kindle wood on it every morning; and he shall lay the burnt-offering in order upon it, and shall make smoke thereon the fat of the peace-offerings” [Leviticus, 6: 5]. And she draws a picture to help us understand what this means. In the desert among the camps of Israel, the tribe of the Levites, and in their midst the tabernacle and the altar on which a fire burns that may never go out. This fire was sent by God himself to the altar. So was this divine fire not all that was needed to burn the sacrifices? But no, every morning the priest would add some wood. The divine fire can only burn for us when we have such divine priests who guard it, who feed the fire without cease, who add firewood without tiring of it. Only then can we be sure that the fire will always burn on our altar. And then, no power in the world can extinguish it.

And after a short silence her voice rings out again. “Many waters cannot extinguish love” [Song of Songs, 8: 7]. Every person has within herself an altar. The heart of each person is a temple, and the fire that burns of its altar is the “Fear of God” and “Love of God”. God starts off this fire on our altar. But we have to guard this spark, to blow on it again and again, without tiring.

And again there is silence. All eyes are turned to the fire. Meanwhile it burns; dry twigs flame out on the ground. Our eyes are burning, too, and maybe something else as well, something invisible, in a secret place, a small and hidden flickering flame. No question about it — each and every one of us knows this about herself, without the slightest doubt.

And suddenly we hear again the familiar voice; “Let the children sing!”

And so we sing. Suddenly we are so overcome with the urge to sing that no power in the world can stop us.

“There is none like our God!”

We sing. Quietly at first, and then louder and louder and from the middle of that song, the tune of a deep prayer rings out:

“Cleanse our hearts so we can serve you in truth!” And ever more beautiful and stronger grows the song, until we are no longer singing — this is a fervent prayer!

And it continues for another minute or two, until some extraordinary longing overcomes our soul, and out of our hearts tear the words “Next year in Jerusalem!”

The tune grows stronger, more emotional, more prayerful. The fire in our eyes grows brighter, more radiant. We add wood to the fire and the flames leap up. We can no longer sit still, we rise. Everyone wants to dance.

And so we dance.

Alongside us dances our leader, Frau Schenirer. Hand in hand with us, together. We dance, we can no longer see anything before our eyes. Our eyes close, our souls pine for something, everything around us disappears. It is so good… Our feet dance of their own accord. And so we dance, strong, stronger, even stronger still.

The dancing lasts for a long, long time, and still dancing we return from the woods. And still we dance. We dance as we accompany Frau Schenirer home, and only later do we ourselves go to sleep.


That was the fifteenth of Av, 1932, in Skawa. A year has already passed since then. We have dispersed, each to her own way. But did the bonds we forged then slacken? No, a thousand times no!

We hold each other by the hand, united in one organization, united just as we were then, as we danced out of the woods with no one seeing us. We are each and every one of us deeply connected with the rest, even as each of us works in our own circle.

A version of this article was previously published as part of The Bais Yaakov Project. It appears here as part of Gesher L’Europa, the National Library of Israel’s initiative to connect with people, institutions and communities across Europe and beyond, through storytelling, knowledge sharing and community engagement.

The Temple Menorah in Kabbalistic Manuscripts

Kabbalistic literature looked for ancient symbols through which it could express its daring innovations. It found such a symbol in the Menorah...

The Sefirot, Temple implements and Jacob’s ladder, 14th c. Russian State Library, (Ms. Guenzburg 82)

Are the branches of the menorah a symbol of the ten Sefirot (divine emanations) in the Kabbalah? This, at least, is what some kabbalists thought.

Like all Jewish innovators before them, in order to convey their bold new ideas, the kabbalists adopted Judaism’s oldest symbols, in this case—the Menorah. Dozens of illustrated examples in manuscripts and in print offer proof.

A pinkas of blessings and prayers, Fürth, 1738, the National Library of Israel, (Ms. Yah. Heb. 143)

How did these kabbalists view the Menorah? In his article “Wisdom, the Eighth Emanation: The Menorah in Kabbalah,” [Hebrew] Moshe Idel discusses two heavenly interpretations of the Menorah. One, developed by the Castilian kabbalist Rabbi Joseph ben Abrhamam Gikatilla, sees the artifact as a symbol of the seven planets. Gikatilla writes, “Just as the entire Menorah is pure radiance and indeed the candles are intended to illuminate just as the seven planets are intended to illuminate, so the seven candles are analogous to the seven planets.”

The Menorah’s seven branches represented the seven planets according to Gikatilla. The materials from which the Temple menorah was fashioned — gold, silver and copper – in turn hint at the three realms—the upper, middle and lower: “Behold, the secret of the lamp is explained” (Sefer Ginat Egoz, Jerusalem, 1988/89, p. 269).

Sha’arei Orah, Josef ben Abraham Gikatilla, 1485-90, Spain, Bibliothèque National de France (Ms. Oratoire 71)

A more common interpretation sees the Menorah as a symbol of the higher powers, the attributes of God – the Sefirot. Rabbi Asher Ben-David, a kabbalist who lived in the first half of the 13th century in Provence, suggested that the Menorah’s candles “hint at the seven edges,” referring to the seven lower Sefirot.

The seven branches of the menorah were interpreted as the seven lower divine emanations, divided into two groups of three. At their center is the Sefirah of Tiferet (glory), that is the shamash, the middle branch that divides the two halves. Whereas Gikatilla focused on the materials from which the Menorah is made, the kabbalists who interpreted the Menorah as a symbol of the Sefirot focused on the material that lights it—the oil.  The oil and the light of the Menorah provided a solution to the great question of the Kabbalah: How do we reconcile the existence of the one God with the ten Sefirot of the kabbalists?

Asis Rimonim, Shemuʼel Galiḳo, 16 & 17th centuries, the Russian State Library, (M.s Guenzburg 170)

In ancient times, the Menorah was a sign and a symbol of the divine presence—the Shekhinah that rests over the Temple, and over all of Israel. The Kabbalistic theory separates the hidden God—the infinite—from His attributes and powers revealed in the world—the ten Sefirot that emanate from the infinite.  The oil poured into the seven branches and the light that is lit from them are, as Idel writes, “the abundance which comes from infinity, which is absorbed by the mid-line, which divides them among the six Sefirot, or edges.”

The shape of the Menorah according to Psalm 67, 1558, University of Frankfurt Library, Germany (Ms. Oct. 203)]