Sherira’s fame rests less on his general activities as Gaon than on the Letter which he wrote about the year 980, in response to questions formulated by Jacob ben Nissim, of Kairuwan. One of these questions retains, and will ever retain, its fascination, although the answer has now no vital interest. Historically the Letter has other claims to continued study. To quote Dr. L. Ginzberg (_Geonica_, i, p. 169): “The lasting value of his epistle for us lies in the information Rabbi Sherira gives about the post-Talmudic scholars. On this period he is practically the only source we have.” Without Sherira, the course of the traditional development would be a blank for a long interval after the close of the Talmud. “But,” continues Dr. Ginzberg, “we shall be doing Rabbi Sherira injustice if we thought of him merely as a chronologist.” And this same competent scholar launches out into the following eulogy of the Gaon: “The theories which he unfolds ... regarding the origin of the _Mishnah_ ... and many other points important in the history of the Talmud and its problems, stamp Rabbi Sherira as one of the most distinguished historians, in fact, it is not an exaggeration to say, the most distinguished historian of literature among the Jews, not only of antiquity, but also in the middle ages, and during a large part of modern times.” This must suffice for the general estimate of Sherira’s work. What is of more striking interest is just the one question, the answer to which does not much matter. As Dr. Neubauer formulated the question put to Sherira, it ran thus: “Was the Mishnah transmitted _orally_ to the doctors of the Mishnah, or was it _written down_ by the compiler himself?” Judah the Prince, we know, compiled the Mishnah, but did he leave it in an oral or a documentary form? Was it memorized or set down in script? The answer does not much matter, as I have said, for sooner or later the Mishnah _was_ written out, and it is not of great consequence whether it was later or sooner. And it is as well that Sherira’s answer matters little, for we do not know for certain what Sherira’s answer was! Most authorities nowadays believe that the Gaon pronounced in favor of the written compilation; but this was not always the case. For Sherira’s Letter was current in two versions which recorded opposite opinions. In the French form the oral alternative was accepted, but the Spanish text adopted the written theory. Which was the genuine view of Sherira? There are many reasons for preferring the Spanish version. As Dr. Neubauer points out, “books, letters, and responsa coming from the East, reached Spain and Italy before they came to France and Germany.” Hence the Spanish text is more likely to be primitive; while, when the Letter was carried further, it might easily have been altered so as to fall in with the talmudic prohibition against putting the traditional laws into writing. It will, again, come as a surprise to some to note another argument used by Dr.