Last month I mentioned a recently published book by the Rabbinical Assembly of the Conservative movement which is destined to be the next general’s authoritative guide to Conservative Jewish life. The book, entitled “The Observant Life: The Wisdom of Conservative Judaism for Contemporary Jews,” is edited by Martin S. Cohen.  I’d like to quote from the chapter of Holy Days and Holidays, written by Alan Lucas, addressing a question commonly asked about the festival of Sukkot (beginning this year the evening of September 30) as well as other Jewish holidays — why do we celebrate two Yom Tov festival days at the beginning and the end of the holiday when the Bible only mentions celebrating the festival days for one day.

Rabbi Lucas writes,

This much-maligned practice of an extra festival day deserves an explanation. In ancient times, the holy days were not set by a fixed calendar, but were rather determined based on careful observation of the lunar cycle. In an elaborate system of notification honed over the generations, witnesses would come before a religious court and testify that the new moon had been sighed and then, through a system of messengers and bonfires, the word was spread near and far (Mishnah Rosh Ha-shanah 2:2-5). This system was obviously predicated on the assumption that the entire Jewish population of the world could be reached efficiently by messengers traveling on foot or carried forward by animals, but this stopped being the case early in Jewish history. To make absolutely sure, then, that the “correct” day was never missed, the rabbis of the Diaspora established a two-day festival. Surely one of the days would be the right one! With the establishment of the calendar we now use, however, it became possible to fix the date of each holiday exactly, thereby rendering the doubling of the festivals theoretically unnecessary. Yet, when the issue came before the rabbis even in talmudic times, they refused to cancel what had already been put in place, saying either regretfully or proudly – there’s no clear way to know – minhad avoteinu b’yadeinu, the custom of our ancestors is inviolate and cannot be set aside by changing circumstance (Babylonian Talmud Beitzah 4b). Of course, that is not invariably how things are. Some ancient customs rooted in realities that have long since ceased to exist have indeed been allowed to fall into desuetude, and there is a responsum of the CJLS permitting communities who so desire to observe only one day of the pilgrimage festivals (Proceedings of the CJLS 1927-1970, pp. 1247-1258). This innovative leniency has not gained much popularity in Conservative congregations, however, and, while some congregations observe only one day, most communities continue to observe the two days of each festival outside of Israel as a way of preserving one of the most traditional distinctions between life in the Holy Land and life in the Diaspora.