Journal Watch
Tue, 04/05/2011

Of all the arcana of Jewish life, that most universal instrument, the Jewish calendar, is one of the more enigmatic. Solar? Lunar? Length of month? Two days of a holiday, or one? What about the “leap month”? And whence derives our calendar? Ancient Judaea/Palestine? Babylonia? The Tanakh? The Talmud?

Later rabbinic halachic codifications? And what about the “kalends” and “ides” and “nones” of the ancient world? Whence derives “calendar” itself? Kalends, an exotic-sounding term with a mundane meaning, was the first of the month — hence “calendar.” (And, lest we forget as we hit tax time, kalends was the date, in Roman times as it is now, on which bills are due — hence kalendrium, account-book in Latin.)

What about the Jewish calendar? Our calendar is a lunisolar (that is, it pays attention to both lunar and solar patterns) device consisting of 12 months of 29 or 30 days, with an extra month added seven times every 19 years (the Metonic cycle) in order to reconcile the solar and lunar aspects of the calendar. Why do we need to do this? Because we cannot have Jewish holidays drifting all over the seasons; they must be in the same season every year. But — oops! — the average Jewish year is six to seven minutes longer than the average solar year; our calendar gains one day every 216 years — more or less. Further tweaking is necessary, and on and on ...

Get it?

How did this state of affairs come to be?

Journal Watcher begins his explorations with the beginning — the question of the very beginnings of the Jewish calendar, and among the many articles that have tackled this question is the idiosyncratic “The Beginnings of the Jewish Calendar” (Hakirah, 2009) by Bernard Dickman. The eponymous “beginning” of the calendar, according to Maimonides, dates to the time of the sages of the Babylonian Talmud. But Maimonides — who has been known to make, frequently, assertions without any evidence — provides no data for this particular assertion. And the Babylonian Talmud itself, redacted around the sixth century C.E., makes no mention of a calendar or its rules.

Dickman notes that the earliest confirmed existence of the Jewish calendar dates to the 12th century. But it had to come from somewhere. OK — introduced earlier (358 C.E.), finalized later. But wait — by 358 there was already an official, irreversible calendar. What’s going on? Dickman deftly walks the reader through the somewhat arcane history of calculations and “fixing” of our fixed calendar.

Staying for the nonce in the ancient world, Journal Watcher has often suggested that we Jews have much to learn from the Christian Scriptures. But a fascinating article by Cambridge’s Colin J. Humphreys and Harvard’s W.G. Waddington, scientists both, in “The Jewish Calendar, a Lunar Eclipse and the Date of Christ’s Crucifixion” (Tyndale Bulletin, 1992), turns this notion on its head. Humphreys’ and Waddington’s conceit is that nothing less than the date of the crucifixion of Jesus — astronomically and calendrically uncertain — is learned from the fact of the recording in the Christian Bible of a lunar eclipse immediately following the crucifixion. It happens that all lunar eclipses visible from Jerusalem were calculated for the years around the death of Jesus using the Hebrew lunar calendar. “There was one, and only one, lunar eclipse at Passover time visible from Jerusalem, that of Friday, 3 April, 33 CE.” Other dates for the crucifixion, derived from other data? Forget them, argue Humphreys and Waddington. The Hebrew calendar, as tweaked by the rabbinic leadership, provided a standard of accuracy that was reliable for Christian theological history as well as for Jewish normative matters.

Having said this, medieval scholars, Jewish and Christian both, questioned the antiquity and accuracy of the Jewish calendar. In “Invention and Convention: Jewish and Christian Critique of the Jewish Fixed Calendar” (Jewish History, 2000), Leo Baeck College’s Joanna Weinberg considers two great 16th-century polymaths, the Jew Azariah de’ Rossi (well known for centuries as the author of the magisterial work “Me’or Enayim”) and the Christian Sebastian Münster, both of whom take potshots at traditional calendrical history.

Münster especially undermined the basis of the Jewish fixed calendar in defending calendrical data in the Christian Gospels as contradictory to rabbinic tradition. Uhh, not so fast, cautions de’ Rossi. Münster sloppily used an unhistorical text — in this case a piyyut (a liturgical poem) — to make his case. “Yet de’ Rossi himself is intent on proving the Jewish fixed calendar is a late post-talmudic convention, an iconoclastic approach which was not welcome in certain rabbinic circles.” The calendar had to be ancient! Weinberg, in her peroration, quotes de’ Rossi with respect to the “fixing” of the calendar: “For when [the rabbis] realized that we are unable to have what we desire, they taught us to desire that which we can obtain.”

Good advice, that.

Finally, pulling it all together is a scholarly romp by Purdue’s Solomon Gartenhaus and Arnold Tubis. In “The Jewish Calendar — A Mix of Astronomy and Theology” (Shofar, 2007), Gartenhaus and Tubis, reminding us that the lunisolar calendar “is an example par excellence of ‘time engineering,’” review in highly literate detail the range of theological and normative halachic considerations that played into astronomical calculations that went into the contouring of the Metonic cycle and other calculations. It wasn’t easy, report the authors; amongst the many constraints that the Jewish calendar designer needed to address was the fact that the calendar had to consist of an integral number of days, and of months; that the week needed to have seven — not more or fewer — days; and that the lunar cycle and the solar year each has its own discrete length, which had to be reconciled. The history of how the calendar was crafted, shaped and reshaped makes for fascinating reading in Gartenhaus’s and Tubis’s tour-de-force article.

But Journal Watcher yet ponders the matter of why two days of Rosh HaShanah . . . ?

Jerome A. Chanes is the author of “A Dark Side of History: Antisem-tism through the Ages” (ADL), editor of “A Portrait of the American Jewish Community” (Praeger) and editor of the forthcoming “Whither American Zionism?” (Bar Ilan) and “The Future of American Jewish Religion” (Columbia University Press).