Aaron ben Meïr was a rabbi and a Nasi (head of the Sanhedrin) of the Gaonate in the first half of the tenth century.
The fragments contain an account of a controversy between Ben Meïr and the Talmudic Academies in Babylonia regarding the Hebrew calendar.
[2] Introducing a new rule in the fixation of the molad (lunar conjunction) of the month of Tishri, Ben Meïr in 921 CE decreed that, in the year 922, Passover and the other Jewish feasts should be celebrated two days before the date prescribed by the traditional calendar.
Ben Meïr, however, refused to yield to their injunctions, denying them any authority in astronomical matters; and, owing to his own reputation and that of his family, won the confidence of Jews in many countries.
The exilarch David ben Zakkai had no authority, being neither a learned man nor a very scrupulous one; and of the two academies at Sura and Pumbedita, the former had no head, and the latter was directed by the ambitious Cohen Zedek.
Ben Meïr's failure was chiefly due to the intervention of Saadia, whose opinion on the subject of discussion, expounded in his Sefer ha-Mo'adim written for that occasion at the request of the exilarch, became authority.