Louis Lewin (1868-1941) was born in Znin, Posen, but was raised in Frankfurt am Main. He earned a Ph.D. degree at the University of Heidelberg in 1893 for his dissertation on Rabbi Simeon bar Yohai, and obtained rabbinic ordination at the Hildesheimer Seminary in Berlin. While in Berlin he also studied with Moritz Steinschneider, the noted Judaica bibliographer, at the Veitel-Heine Ephraim'sche Lehranstalt. Lewin followed in his mentor Steinschneider’s footsteps and developed a keen interest in collecting books and manuscripts. After completing his formal education, Lewin returned to Posen where he occupied rabbinic positions in Hohensalza (German, Inowraclaw - Polish), Pinne (Pniewy) and Kempen (Kepno). In 1920 he received life tenure as rabbi of Kattowitz, Oberschlesien (Katowice, Upper Silesia).

Posen (Poznan) and Silesia (Schlesien - German, Slask - Polish) were both areas which had alternated for centuries between Germanic and Polish rule. After World War I, most of Posen and Silesia became part of Poland. Antisemitism in both regions grew, encouraging migration westward to Germany, other parts of Western Europe, and the United States.  At the request of his community in Kattowitz, which officially came under Polish rule in 1922, Lewin publicly refuted antisemitic attacks published in a Polish newspaper. He subsequently received an anonymous assassination threat. This event spurred his move in 1925 to Breslau (Wroclaw), a community that was still in Germany at the time. Lewin held many prestigious posts in Breslau: director of a Jewish educational institution called “Rhedigerheim;” the rabbi of the Abraham Mugdan synagogue; an adviser for the Judisches Museum Breslau; and a member of the editorial board of the Monatsschrift fur Geschichte und Wissenschaft des Judentums. 

Lewin was a prolific author and wrote extensively about the history of Jewish communities in Posen and Silesia. A complete bibliography of Lewin’s writings is in Kiryat Sefer, vol. 19 (1943), p. 114-116.  In 1939, Lewin moved to Bnai Brak, Israel, where he lived until his death in 1941.

The Aaron Etra Collection

The Aaron Etra Collection held in the Special Collections of Yeshiva University consists of rabbinical manuscripts and sermons, letters, yizkor books, communal and accounting records, circumcision records, seals, amulets, and other materials, chiefly from Posen and Silesia, originally collected by Louis Lewin. Lewin was a tireless researcher and copied extensive portions from archival and manuscript material in repositories in Breslau.  These handwritten notes have become especially valuable since some of the originals did not survive World War II.

Louis Lewin carefully recorded descriptions of all the treasures in his Collection, and his handwritten catalog, in German Gothic script, is owned by the Central Archives for the History of the Jewish People in Jerusalem. Lewin’s son, Rabbi Dr. Daniel Lewin, transferred the Collection to London in the late 1930s, thus preserving the manuscripts for posterity. The Collection was purchased by Yeshiva University in 1948 through the efforts of Isaac Lewin, a professor at the Bernard Revel Graduate School, with funds provided by the Etra family, and the Collection was named in honor of the late Aaron Etra.
Descriptions of the rabbinic material in the Collection are available in Osef kitve-ha-yad ha-rabaniyim: Sifriyat Mendel Gottesman, Yeshivah-Universitah (Rabbinic Manuscripts: Mendel Gottesman Library, Yeshiva University), by Joseph Avivi, translated by G. Hirshler, trans. Condensed and revised by P. Berger (New York: Yeshiva University Library, 1998).  Descriptions of all the Lewin manuscripts appear in the YULIS catalog.