ambiguities of shared ritual authority. That is, while rabbis and laity must both pass on the same religious issues, each side has its own distinct role to play in the determination of practice. The rabbi, in the liberal as well as the orthodox setting, is the authority of textbook law, the scholar who declares and interprets for the congregation the rules and principles that govern the institutions of Jewish observance. The laity, for its part, is the creator and guardian of minhag, a thoroughly legitimate source of Jewish law. Neither side, in other words, needs to be"boss." The task of both is to maintain the conversation between halakhah and minhag which has a long and honored history in the literature of rabbinic law. The following three examples can help illustrate this conversation, the encounter between religious observance produced by the dynamic of Jewish life and the existing halakhah as understood by the community’s teachers.
1. HALLEL ON ROSH HODESH.
R. Yohanan said in the name of R. Shimeon b. Yehotzadaq: on eighteen days an individual recites the entire(gomer bahen) Hallel. They are: the eight days of Hanukah , the first day of Pesah , and Shavuot . In the diaspora, there are twenty-one days(counting an extra day of yom tov for Shemini Atzeret , the first day of Pesah , and Shavuot ).
This requirement, understood by most authorities as a rabbinic taganah,'? does not apply to the remaining days of Pesah and to Rosh Hodesh. The Talmud explains that the concluding days of Pesah , unlike the intermediate days of Sukkot and Shemini Atzeret , are not distinguished one from the other in the number of sacrifices to be offered; Rosh Hodesh, meanwhile, is not a"hag," a day on which work is forbidden. For this reason, the early amora Rav, was surprised when, coming to Babylonia from Eretz Yisrael, he saw the people recite Hallel on Rosh Hodesh. He intended to protest this practice, but when he saw that only the half-Hallel
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