the title Sefer She'elot u-Teshubot (Leipzig, 1860). Work Toward the end of his life, about 1260, Isaac composed his ritual work Or Zarua. He is usually quoted as "Isaac Or Zarua." It was printed from the Amsterdam incomplete manuscript by Lipa and Höschel in Jitomir, 1862. Other manuscripts are at Oxford and in the Jewish Theological Seminary in New York City. In the edition of Lipa and Höschel Seder Nezikin is wanting; most of the rest of the work was afterward printed at Jerusalem by J.M. Hirschensohn. The Or Zarua comprises the whole ritual, and is arranged according to the Talmudic tractates, while at the same time the halachot are kept together. The author, unlike Maimonides in his Mishneh Torah, does not confine himself to giving the halachic decisions, but gives also the passage of the Talmud, explains the subject matter, and develops the din from it. Thus the Or Zarua is at the same time a ritual code and a Talmudic commentary. As it contains, in addition, explanations of some passages in the Bible, the author is also quoted as a Bible commentator. Moreover, the book contains a part of the halachic correspondence which the author carried on with Talmudic scholars of Italy, France, and Austria. Older collections of halachic decisions which the author had gathered together during his lifetime seem also to be embodied in the work. Isaac explains unknown words in Bohemian (i. e. Czech), his mother tongue, and cites the Jerusalem Talmud, to which he ascribes great authority in halachic decisions. The work is introduced by a treatise couched in words to whose meanings mystical significance is attached. It is an imitation of the Alphabet of Akiba ben Joseph, and was composed at the order of Isaac's teacher Eleazar ben Judah of Worms. Isaac's son Chaim Eliezer arranged a compendium of this work which exists in several manuscripts. The Or Zarua succeeded in displacing all the older ritual works. It is very important also for the Kulturgeschichte of the German Jews in the Middle Ages. According to Gross, Isaac's chief importance rests upon the fact that he introduced among the Jewish communities in Slavic lands the study of the Talmud from France and the west of Germany. Isaac was of a mild and peace-loving character and it was for this reason, perhaps, that he did not participate in the struggle against the study of secular sciences,