although this is implicit already in a fourth-century Babylonian tradition.^116
At some stage before the eighth century, afixed 19-year cycle of intercalations
(similar to the standard Babylonian cycle, but based on a rule of the equinox)
was also adopted. By the early tenth century, the rabbinic calendar had
become the definitive,fixed scheme that is still normative among the Jews
today (Stern 2001: 191–210).
The transformation of Jewish calendars in late Antiquity from empirical
andflexible procedures to calculated andfixed schemes calls for an explana-
tion. The introduction of a month beginning from the conjunction and of a
rule of the equinox may have followed the Christianization of the Roman
Empire, more particularly of Palestine, in the fourth centuryCE: rabbis and
other Jews in this period may have adopted the lunar calendar principles
which the Christians had used already earlier in their Easter cycles, even if the
latter’s purpose, paradoxically, had been precisely to distance themselves from
Jewish calendrical practice.^117 But in the specific context of the rabbinic
calendar, the adoption of calendar rules and eventually afixed calendar is
best explained as the outcome of the unique relationship between the Pales-
tinian and Babylonian rabbinic communities. These communities considered
it essential to observe festivals and fasts, and generally to reckon the calendar,
on exactly the same dates—a quest for unanimity that was unique to the
rabbinic movement, and never pursued elsewhere in the variegated Jewish
Diaspora world. Because of the impossibility of communicating the results of
empirical new moon sightings from Palestine to Babylonia and thus of
ensuring the observance of festivals in both communities on the same dates,
it became a necessity—especially at a time when the rabbinic community in
Babylonia began to develop, from the third centuryCE—to increase the
predictability of the Palestinian rabbinic calendar by restricting it withfixed
rules. The gradualfixation of the Palestinian rabbinic calendar was thus the
result of an attempt to unify and standardize the calendar of the rabbinic
communities of Palestine and Babylonia.^118
Beyond these specific explanations for the evolution of the Jewish calendar,
consideration must also be given to broader, macro-historical processes. As
has been noted above in this chapter and frequently elsewhere in this work, the
(^116) Sixth-c. evidence: ibid. 182–4, where I overlooked a tradition (attributed to the‘Nehar-
deans’, who are usually associated with the 4th c.CE,inbSanh.41b–42a) that the full moon
occurs on the 16th of the month, which implies a month beginning at the conjunction.
(^117) Ibid. 222–6 (on the rabbinic calendar). For a similar argument regarding the Serdica
document, see ibid. 141–3 and discussion below. At the end of Ch. 5, I have argued that in late
Antiquity Easter cycles may have similarly influenced non-Jewish lunar calendars in Persian
Mesopotamia.
(^118) Ibid. 232–56, and on the active role that the Babylonian community played in the
formation of thefixed rabbinic calendar, 257–75. A similar process of unification and standar-
dization affected the date of Easter in Constantine’s Christian Empire: see Ch. 7.
Dissidence and Subversion 335