Thursday, November 27, 2008

History - What is a week?


By journalist/translator/illustrator

R' Avraham Broide,

At first glance, the "week" seems the odd-man-out of our calendar.

Because unlike the year that is measured by earth's yearly spin round the sun, or the month that is measured by the moon's journey round earth, the week seems disconnected from astronomical phenomenom. Its significance stems from Hashem creating the world in six days and resting on the seventh.

Is this why Shabbos is more sacred than other other day of the Jewish year?


Digging a little deeper, however, one soon discovers that the week has a celestial connection after all. This is evident from a couple of Gemaras where Rashi points out a clear correlation between the heavenly bodies and the seven days of the week.

For thousands of years, stargazers, astrologers, and astronomers noticed that almost the stars of the heavens are nailed in place against the backdrop of outer space. They march in unison across the heavens, never daring to make a misstep.

But gaze into space for consecutive nights and you might notice five rogue stars that disobey the rules, inching slowly between the stars. Some of them even backtrack during the process. The ancients named these stars planets, ancient Greek for "wanderers." The rabbis called them kochvei leches, wandering stars.

In fact, they are not stars at all, but planets circling their way around the sun as we do.

Add the sun and moon to these five planets and you get seven heavenly bodies. Chazal and the ancients arranged them in this order:

1. Shabtai (Saturn). 2. Zedek (Jupiter). 3. Maadim (Mars). 4. Chammah (the sun). 5. Kochav Nogah (Venus, the shining star). 6. Kochav (Mercury). 7. Levanah (the moon).

The Gemara (Berachos 59b) states that G-d created the heavenly bodies at the beginning of Wednesday night during the hour of Shabtai (Saturn). Rashi explains:

At this moment, when G-d placed the sun, moon and stars in the firmament, the seven heavenly bodies began their rule. And forever after they rule in the following order:
Saturn rules during the 1st hour, Jupiter the 2nd second, etc. Once the seven planets have run their course, the cycle starts again. Shabtai takes the 8th hour, Zedek the 9th, and so on.

It takes exactly a week for the cycle to work through all its permutations. After one week, Shabtai returns to the first hour of the day on Wednesday evening and the cycle repeats itself exactly like the week before.

Yet another Gemara connects the weekdays to the seven heavenly bodies.

The Gemara (Shabbos 129b) warns people never to perform bloodletting on Tuesdays, because on Tuesdays, Mars rules during an "even" hour. What does that mean?

Rashi explains:

If you calculate which heavenly body rules during the first hour of each weekday, the order is as follows:

Sunday - the sun. Monday - the moon. Tuesday - Mars. Wednesday - Mercury. Thursday - Jupiter. Friday - Venus. Shabbos (Saturday) - Saturn. (Do you see a pattern?)

Since Mars, symbol of the sword, pestilence and tribulation, falls during the first hour of Tuesday, seven hours later it will automatically fall during the eighth hour of the day. Eighth is an even number. Since even numbers are dangerous (as explained in the Gemara Pesachim 110b), one must avoid bloodletting the whole of Tuesday in order to avoid this planet-promoted hazard.

We see from all this that the names Sunday, Monday, and Saturday are no coincidence. They are named after the heavenly bodies that have ascendancy during their first daylight hour!

In fact, the Babylonians named every day of the week after gods associated with these "first hour" heavenly bodies, as follows:

Shamash (Sunday), Sin (the moon, Monday), Nergal (Mars, Tuesday), Nebo (Mercury, Wednesday), Marduk (Jupiter, Thursday), Ishtar (Venus, Friday), Ninurta (Saturn, Saturday).


If so, you might ask, how can Jews mention weekday names that are based on idolatry? Does the Torah not command (Shemos 23:13), "The names of other gods you shall not mention, they shall not be heard on your mouth?"

Discussing whether one is permitted to mention the names of coins named after idols, the Responsa Chavos Yair (chapter 1) mentions a few mitigating factors, including the permissibility of mentioning names of idols that are obsolete and no longer worshipped.

However, the Tzitz Eliezer (volume 8, chapters 8 and 14) objects to non-Jewish month-names due to their idolatrous connotations, and suggests writing 01, 02, etc., instead of their names. How he would get around the problem of saying weekday-names is unclear.

How did our modern weekdays develop? Some of them were altered by the Greeks and Romans when they substituted some of the Babylonian gods with their own, and later still the Teutons and Anglo Saxons threw out the Roman gods and substituted them with their own idols. As a result, the modern names of Tuesday, Wednesday, Thursday, and Friday, are named after obsolete Teuton and Anglo Saxon gods.

Wednesday, for example, started as Nabu in Babylon, became Mercurius in Rome, and ended up as Woden in Britain. Woden transmuted into modern day Wednesday.


  1. The correspondence of the moving celestial bodies to the days of the week is still clear in Japanese.

    Nichi-youbi - Sunday (Nichi = Sun)
    Getsu-youbi - Monay (Getsu = Moon)
    ka-youbi - Tuesday (ka-sei = Mars)
    sui-youbi - Wednesday (sui-sei = Mecury)
    moku-youbi - Thursday (moku-sei = Jupiter)
    kin-youbi - Friday (kin-sei = Venus)
    do-youbi - Saturday (do-sei = Saturn)

    This nomenclature was adopted from the Chinese (although it's no longer popularly used in China), who in turn seem to have adopted it from Mesopotamia via the Romans, Manicheans, or through India.

  2. I think one can still make the argument that the week is still lemaalah min hatevah. The existence of a cycle of weeks require people to do the counting. Without people counting days, the week as a unit of time simply disappears.

    The number seven corresponds to a natural phenomenon, but the week is still not as "natural" as the day, which is intrnisically connected to the solar cycle, or the month, which is intrnisically connected to the lunar cycle, or the year, which is intrinsically connected to the cycle of the seasons.

  3. You are correct. I am only pointing out the novel fact that (as you write) there is a connection between the weekdays and the celestial bodies. Although the Gemara writes that the seven hours factor is intrinsic to creation, naming the days after the first hour ruling body may be non-Jewish convention and have no deep significance.

  4. The conjunction of the 7 hour cycle and the 365.25 day year creates a 7 year cycle as well.

  5. I'm more moved by R' Yehudah haLevi's explanation -- it proves the week is older than man's separation into cultures. Something Adam first encountered would echo across the globe without needing to invoke mystical significance.



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