Inevitably, the holidays, weekly celebrations (Shabbat) and monthly celebrations (Rosh Chodesh) of the Jewish calendar sometimes overlap. In some instances, the holiday overrides the regular celebration (e.g. on Rosh Hashana, the first day of Tishrei, Rosh Chodesh Tishrei is not mentioned). In other cases, the regular celebration takes precedence (e.g. if Tisha b’Av occurs on Shabbat, the fast is postponed until Sunday).

Two or three times a year, however, Rosh Chodesh and Shabbat overlap. Such is the case this week, when the month of Shevat begins on Shabbat (tomorrow).

Because Rosh Chodesh is marked largely through the addition of special prayers (such as Hallel), the Shabbat Rosh Chodesh service is significantly longer than the normal Shabbat service. (There are special additions to Birkat Hamazon as well). One of the most interesting of these changes is the haftarah (reading from the Prophets) designated to be read on every Shabbat Rosh Chodesh: the final chapter (66:1-24) of the Book of Isaiah.

It has been suggested that this chapter was chosen because of its penultimate verse, which mentions both Rosh Chodesh and Shabbat: (66:23) “And it shall be that, from New Moon to New Moon, and from Shabbat to Shabbat, all flesh shall come to prostrate themselves before Me, said God.” The chapter itself, however, can be read as both a consolation and inspiration for those who have remained faithful to God. In this final chapter of Isaiah, God promises that the wicked shall receive retribution and the faithful shall live and endure. The moon, with its waxing and waning, is a potent and ever-present symbol of such a promise and is thus integral to the celebration of Rosh Chodesh.

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