
A celebration of the holiday Simchat Torah in Israel, where scrolls of the Hebrew Bible are paraded around the synagogue by the entire congregation. Simchat Torah is the last in a monthlong series of celebrations and solemnities surrounding the Jewish New Year. Image credit: avital pinnick via flickr.
I sometimes wonder how anyone ever kept track of Jewish holidays without smart speakers. “Hey Google, when is [fill in the next Jewish holiday] this year?” is a question I ask on the regular.
For instance: At my Reform temple outside of Cleveland, 2022’s “holiday season” started on September 17 with a Selichot service meant to ask forgiveness for the past year’s sins. Selichot, a service most non-Jews (and many Jews) have never heard of, is a kind of dress rehearsal for really asking forgiveness when things are in full swing between the Jewish New Year, called Rosh Hashanah in Hebrew, and the Day of Atonement, a.k.a. Yom Kippur. It’s to focus the mind for what ends up being about a month of holy days emphasizing reparation and renewal. That month ended, for the Jewish year 5782, on October 17, 2022 with Simchat Torah – when Jews finish our annual reading of the Hebrew Bible and start back at the beginning again.
But in 2023, Simchat Torah will be on October 7. And in 2024 it will be on October 24. And the following year it will fall back to October 14. All of those dates in our customary Gregorian calendar will be exactly the same date in the Hebrew calendar: Tishrei 23.
While many of us are aware that different cultures have different calendars, we don’t normally spend much time wondering how these varying systems of reckoning came to be. I always assumed that annual agricultural rhythms shaped menology wherever it developed, and there is a great deal of truth to that.
But in the case of the Hebrew calendar, a tribal confederation shifted from one set of food production rhythms – the inundation of the Nile and its resulting harvests – to a cadence based on periods of rain and heat in the Land of Israel. The inherent difficulties of this change may have helped maintain the continuity of Jewish culture over the millennia.

An image from the magnificently-decorated Tomb of Sennedjem, a respected artisan in ancient Egypt’s New Kingdom. It shows Sennedjem and his wife harvesting their fields. Image credit: Kairoinfo4u, via Flickr.
The idea that switching calendars preserves continuity might seem like a strange one. I used to assume that the stiff-necked obstinacy of the Jews had perpetuated the oddness of the Hebrew year – but now I believe the opposite. I suspect that the struggle to get everyone onto the same page of the calendar, so to speak, may have forced religious leaders into a heightened awareness of temporal organization. It might have been this awareness that contributed to the intactness of the Jewish people into the 21st century.
My change of mind started as I was getting to the end of my novel Midbar, during a scene in which one of my teen protagonists is scribing the last words of his revered teacher. The teacher’s words are a version of the Ten Commandments, and when I got to the one usually translated as, “Six days shall you labor, but on the seventh day you shall rest” (Exodus 34:21), I realized that a vast, unacknowledged transformation must have taken place in the years between when Semitic tribes labored in Egypt and the time when the commandment to keep the Sabbath was included in the canon.
That’s because the ancient Egyptians had a ten-day week: nine days of work and one of rest. Their months and year were about the same lengths as ours, 30 days and 12 months, but each month only had three weeks. This contrasts with the Babylonians, who had seven-day weeks, four to a month, with the holiest day being the last day of the week. By the time the earliest version of the Ten Commandments was written down, about three thousand years ago according to biblical researcher Michael Coogan, the change from the Egyptian calendar to the Babylonian must have been just about complete.
The idea of specifically the seventh day being a day of rest is stated in all three versions of the Ten Commandments in the Hebrew Bible, one of the few tenets they hold in common. To me, this smacks of protesting a bit too much. God is extra-specific in Ex. 20:9-10, emphasizing that the holy Sabbath (already referenced just one verse earlier) is on the seventh day after six days of work. That meticulousness is echoed in Deuteronomy 5:13, where the commandment to “observe the Sabbath day by keeping it holy” (Deu. 5:12) is followed by a reminder that the sabbath is on the seventh day. The oldest version of the ordinance, in Exodus 34, doesn’t even mention the Sabbath – it just forbids labor on the seventh day under any circumstances.
There could have been Israelites still organizing their months into three 10-day weeks even after the Hebrew Bible began coming together, necessitating an emphasis on the seventh day, instead of the tenth, being holy.
All of this textual precision may well be a sign that the ingrained habits of longer weekly cycles died hard – especially after centuries of Pharaonic hegemony in the Kingdom of Israel. Egyptian rule may even have continued in the coastal city of Jaffa up until shortly before the Exodus 34 version of the Decalogue was committed to writing. There could have been Israelites still organizing their months into three 10-day weeks even after the Hebrew Bible began coming together, necessitating an emphasis on the seventh day, instead of the tenth, being holy.
Making a shift in the calendar might seem nit-picky to us reading about it now. But just consider what a nine-day work week with a one-day weekend would feel like if we 21st century folk decided to switch to it by, say, 2035. We’d have to figure out three more names for days of the week. We’d probably end up working shorter hours per day. What would vacations look like? The rhythms of the entertainment industry, the hospitality industry, sports, school, family? The ramifications for the economy alone are impossible to project.
Certainly, if such a metamorphosis were to be effective, it would bind our society closer together. Everyone who could remember the way things were, and who had contributed to making the transition work, would have shared a life-changing experience in common. And overcoming what would likely have been vehement resistance would have taken a pretty comprehensive effort, verging on dictatorship, on the part of leaders at every level of society.
I’m not suggesting that revolutionizing the number of days in a week is possible today, or even that it might be a good idea. I’m just trying to imagine what Jewish leadership managed to pull off three thousand years ago in terms we can relate to. The structure of the calendar is such a bedrock assumption of our day-to-day lives, it’s hard to wrap our heads around what it would mean to radically reform it. And yet I am convinced that this happened, and not particularly gradually, around the time when some Semitic tribes living in hills along the eastern Mediterranean began to coalesce around a set of texts they considered sacred.
Shared change forms new and powerful bonds. The Exodus is nothing if not a chronicle of shared change. We are surely far from the verge of adding Hexadays, Septadays and Octadays to our work week after Fridays; but I often wonder whether we are the next human culture to go through the kind of revolution that the ancient Israelites did when they chose their calendar. And whether our own civilization, in the throes of a transformation every one of us can feel and breathe, will last as long afterward.

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