Sherira's letter (henceforth:
Iggeret), in its length, takes the form of a short book. In it, Sherira endeavored to answer an inquiry from
Kairouan about the authorship and composition of the
Mishnah and
Talmud, and in particular why earlier authorities are seldom cited by name and the authorities that are so cited do not seem to be chronologically continuous. Sherira is one of the first to present a detailed discussion on the
Savoraim, including their activity in revising and finishing the Talmud. The letter he wrote is the chief source for the history of the Talmudic, post-Talmudic, and geonic periods.
Jacob ben Nissim of Kairouan addressed, in the name of his community, a number of questions of historical interest to Sherira, inquiring especially into the origin of the Mishnah and the sequence of the redactions, the origin of the
Tosefta, and the sequence of the Talmudic, post-Talmudic, and geonic authorities. The reply seeks to clarify the basic principles upon which the chain of transmission of the
Oral Law is founded. Sherira clearly and lucidly answers all these questions, throwing light upon many obscure passages of Jewish history. This historical responsum, which is composed half in Aramaic and half in Hebrew, reveals Sherira as a true chronicler, with all the dryness and accuracy of such a writer, though his opinions on the princes of the Exile belonging to the branch of
Bostanai, as well as on some of his contemporaries, are not entirely unprejudiced. As narrator of the history of Halakhah in the course of the first millennium. The literary topoi of his historical account have some parallels to the Islamic historical genre – the
ṭabaqāt. As a chronicler, he exposes monumental documented information about the rabbis and the Babylonian communities, especially the Jewish seats of learning (
academies) at
Sura and
Pumpeditha. Sherira also relates to the persecution under
Yazdegerd II. Apparently, he also refers to some mythical imagery while reconstructing the chronology of the Halakhah as a profound historical picture. This letter is included in the
Ahimaaz Chronicle, but it has also been edited from manuscripts by B. Goldberg and under the title "Iggeret Rab Sherira Gaon"; also by J. Wallerstein, under the title "Sherirae Epistola." The best edition of this letter prior to 1900 is that by
Adolf Neubauer. The best modern source for the letter is the edition of B.M. Lewin, in which the French and Spanish recensions are printed side by side. Most later editions are based on one or other of these. All dates appended in Sherira's work are according to the
Seleucid era counting. Modern translations of the
Iggeret have converted these dates into their corresponding
Gregorian calendar date for easy comprehension. Another letter by Sherira, also addressed to Jacob ben Nissim of Kairouan, deals with the various titles given to the Talmudic sages, as "Rabban," "Rabbi," "Rab," and "Mar," and explains why some sages are simply mentioned by their names, without the addition of any titles. ==Editions==