underpinnings. For example, he explained why the Jewish belief in revela-
tion did not belie the primacy of reason. Revelation, he argued, augmented
the human power of reason. Theoretically, he suggested, it was possible to
grasp the divine will through reason alone. Revelation provided a means to
accomplish this task for those who lacked the intellectual ability to reason
philosophically or rationally. Revelation also provided a shortcut to rational
truth – that is, something to believe in while trying to understand the
divine will philosophically.
The cultural and intellectual achievements of Sa’adia Gaon and other
Babylonian Jewish scholars, however, did not ensure the predominance of
Babylonian Jewry. Beginning in the 920s, Sa’adia played a major role in the
two arduous struggles waged by the Babylonian Gaonate, the first against
the Gaonate of the Land of Israel over the right to determine the calendar, the
other against the Karaites (see below) over the exclusive authority of the
Babylonian Talmud. In 920, Rabbi Aaron ben Meir and the rabbinate of
the Land of Israel attempted to revive and reclaim the rabbinate in the Land of
Israel’s practice of determining the Jewish calendar on a monthly and yearly
basis, a practice that had been discontinued nearly six hundred years earlier.
This was no small challenge. The uniformity of the Jewish calendar
allowed Jews to travel anywhere in the Jewish world safe in the knowledge
that festivals and fast days would be observed on a given day. The ability to
determine the calendar was a foundation stone of world Jewish leadership. In
a larger sense, the dispute reflected the discontent of the Gaonate in the Land
of Israel at the Babylonian effort to usurp world leadership. More specifically,
in 835, the gaon of Sura had solicited instruction from the rabbis in the Land
of Israel regarding the calendar, only to then claim superior knowledge of and
authority over it, in the face of Amoraic statements that reserved the right to
determine a Jewish leap year to the rabbis in the Land of Israel.
Buttressed by the support of an Egyptian sovereign trying to assert his
independence from Abbasid rule, ben Meir reinstated the older calendar prac-
tice over the objections and condemnations of the Gaonate. Unprecedented in
the history of the diaspora before or since, in 921 the Jews in the Land of
Israel followed a different calendar and observed holidays on different days
than the rest of the Jewish world. In response, Sa’adia Gaon published Sefer
ha-Mo’adim, a compendium of laws concerning the Jewish calendar and festi-
val. In addition, he spearheaded a campaign to win the support of the Jewish
world for the Babylonian rabbinate. By 923, Sa’adia Gaon had persuaded ben
Meir and the other rabbis to acquiesce.
Nonetheless, this episode demonstrated the limits of Babylonian hege-
mony as late as the early tenth century. The calendar controversy might not
have been so contentious had it not taken place against the background of a
second, larger challenge to the authority of the Babylonian Gaonate:
Karaism. The Karaites were a sectarian movement that originated in the
66 The Jews of Islam