On Memory, Calendars, and Rituals
For much of my life, people have told me that I have an unusually good memory. I’m competitive enough that I have appreciated the compliment while being somewhat disappointed by thinking that I could be even better at recall if everyone remembered as well as I do, motivating me to work harder at it.
Retrieving memories gives me pleasure. One of the ways that my mind has tagged memories for retrieval is by the calendar. I don’t remember making a conscious decision to store memories that way, but it seems that I was genetically predisposed—my father, currently in his late 80s, is still pretty good at calendar-assisted recall, as was his mother at a comparable age.
These observations serve as background to memories triggered by this year’s synchronous occurrence of the September equinox and the Jewish holiday of Yom Kippur on September 23. Although the Jewish traditional calendars are based on lunar cycles, as opposed to the solar-based Gregorian calendar, which has become a de facto world standard, an astronomical coincidence causes the calendars to meet every 19 years. Thus Yom Kippur falls together with or near September 23 and the equinox every 19 years.
I wrote up a more detailed discussion of solar and lunar calendars and how they come together, but decided that it might provide more information than some readers would want, so I’ve placed it at the end of this piece, after the memories of previous equinoctial Yom Kippurs.
In 1977, Yom Kippur and Equinox fell on September 22, less than two weeks after I had moved to the commune where I would spend the next eight years. The focus of my ritual observance was the equinox, as I was part of group that marked the event by spending the entire night outdoors on a hillside. I remember the timeless ritual of sitting in a group around a bonfire; receiving a rude gesture from a future romantic partner in response to what might be considered a miscommunication on my part; and taking on the middle of the night task of waking up a snorer who was keeping everyone else from falling asleep.
Nineteen years later, in 1996, Yom Kippur fell on the same day as this year, September 23, three days after I arrived in Santa Fe, the day after the equinox, and the day before I started work. The friends who had accompanied me and the rental truck filled with my possessions across the country had stayed the night, then driven north towards Colorado and their own adventures. The dictates of hospitality had deferred my initial investigation of the Farmers’ Market until the following Saturday. I still found the high desert environment of north central New Mexico fresh and startling. On Yom Kippur itself, we took a walk down to the river, where the bright yellow chamisa was in bloom, and I contemplated the new life that I was starting.
Nineteen years from now, in 2034, Yom Kippur will again fall on September 23, although the equinox will occur before sunset on the 22 for most of North America including Santa Fe. I hope that the coincidence of calendars will again open a window to a trove of memories.
More on Distinctions and Overlaps among Calendars
This year the sun could be seen directly overhead at the equator in its apparent southbound movement at 8:20 AM Universal Time (sometimes expressed as Greenwich Mean Time) on September 23, which was the equivalent of (more or less) sometime between 8:20 PM on September 22 and 8:20 PM September 23, depending on your local time zone. This moment was what would technically be considered the September equinox (the gateway to autumn in the Northern Hemisphere, to spring in the Southern), although most of us associate each equinox or solstice with an entire day or even several. September 23 was also the date on which Jews around the world observed the holiday Yom Kippur, a day comparable in its solemnity to Good Friday for Christians, although the narrative from which the solemnity derives is completely different.
Yom Kippur always falls on the tenth day of Tishri (or Tishrei), the first month of the Jewish civil calendar. As opposed to the predominant Gregorian calendar, which was designed to have solar-oriented events such as solstices and equinoxes be associated with consistent dates from year to year, the Jewish calendars are primarily lunar-oriented, with the first of each month calculated to coincide with the new moon, the 15th with the full moon, and each month thus lasting 29 or 30 days (on the average, a complete lunar cycle is 29.5309 days). As with the lunar Islamic calendar, the new day begins at sunset, the prelude to the twilight time when the new sliver of crescent moon can first be spotted.
The 12 months of the Gregorian calendar contain 365 days three quarters of the time and 366 for leap years. The closest that a lunar-based calendar comes to that is 12 months totaling 354 or 355 days. There is significant variation among Muslim countries & populations in deciding the day when the new month starts, but all versions lead to a mix of 354- and 355-day years, with no attempt to reconcile to the “tropical” solar year of approximately 365.24 days. In contrast, the canonical Jewish calendar adds a leap month every two or three years, preserving an approximate synchronicity with the Gregorian calendar over a span of a century or two. In fact, as the ancient Athenian astronomer Meton calculated, the amount of time that elapses over the course of 235 lunar monthly cycles is just two hours or so more than the amount of time in 19 solar years (this is known as the Metonic Cycle after its promulgator). Using this information, the Jewish calendar was engineered to a 19 year cycle of 12 regular and seven leap years, so that Yom Kippur or any other Jewish date falls on or within a day of the same Gregorian date every 19 years.