MANN, JACOB (1888–1940), scholar of the *Genizah period and of the Jews under the *Fatimids, and particularly of the Genizah fragments. The son of a shoḥet from Przemysl, Galicia, where he received a traditional Orthodox education, Mann went to London in 1908 where he pursued his secular studies. At the same time he pursued rabbinic studies at Jews' College and qualified for the ministry in 1914. Soon after, he began publishing learned papers, including his excellent series, "The Responsa of the Babylonian Geonim as a Source of Jewish History" (in jqr, 7 (1916/17); 11 (1920/21)). The field in which he was later to distinguish himself as a great scholar was Genizah research. Mann for the first time undertook to collect and explain all the documents from the period preceding the Crusades to the fall of the Fatimids. His book, The Jews in Egypt and in Palestine under the Fatimid Caliphs (2 vols., 1920–22; reprinted with introd. by S.D. Goitein, 1970), was a masterpiece sui generis. By establishing the dates of a great number of the largely undated Genizah documents, Mann provided the chronological framework for the history of the Jews in the Near East. He revealed the great role played by the *Jerusalem gaonate in the period before the Crusades and shed new light on the various forces within the Jewish communities then living in the lands ruled by the Fatimids. Although Mann neglected the Arabic documents, abstained avowedly from drawing general conclusions, and was mainly interested in the communal history of the Jews, his work is of lasting value as a great collection of hitherto unknown sources, which he ably deciphered and annotated. After the first volume of the above-mentioned book appeared, Mann went to the United States, first as lecturer at Hebrew College in Baltimore and a year later as professor at Hebrew Union College in Cincinnati. There he taught Jewish history and Talmud and continued his research. His second major work, Texts and Studies in Jewish History and Literature (2 vols., 1931–35, repr. 1970), contains various documents concerning European Jewry and Geonica and texts elucidating the history of the *Karaites in the Near East and in Eastern Europe. In the last years of his life Mann embarked on the study of one of the most difficult branches of Hebrew literature, the Midrashim. In his work, The Bible as read and preached in the Old Synagogue; a study in the cycles of the reading from Torah and Prophets, as well as from Psalms and in the structure of the Midrashic homilies, he tried to establish the dependence of the Midrashim from the chapters of the Torah and from the haftarot which were read on the Sabbath on cycles of three and one-half years respectively. The first volume of the book was published in 1940. Material left by Mann for the second volume was prepared for publication by Isaiah Sonne; after the latter's death the work was continued by Victor Reichert; it appeared in 1966.
R. Mahler, in: Yivo Bleter, 16 (1940), 170–81, incl. bibl.; 17 (1941), 92.