Throughout this year we all noticed that the holidays were celebrated earlier than usual. The fact that Hanukkah, for example, coincided with Thanksgiving, made it clear that this is an intercalation year in which an adjustment will have to be made to assure that the Jewish holidays will be celebrated in their seasonal time. Rosh Ha-Shanna should fall in the autumn. Hanukkah should be celebrated during the dark days of winter. Pesach should mark nature's renewal in the spring and Shavu-ot should be in the beginning of summer.
The adjustment of the Jewish calendar was designed by Rabbi Hillel II (359 CE) and is called ibur ha-shannah. Shannah in Hebrew means 'year' and ibur means 'intercalation', 'conception' and 'growth'. The word is derived from the verb iber meaning 'impregnate' (Job 21:10). Shannah me-u-be-ret is an intercalation year, a leap year, the year in which an extra month is added in order to adjust between the lunar cycle of 354 days and the solar cycle of about 365 and a 1/4 days. The month added to the calendar is Adar, the very same month in which we celebrate Purim. The reason Adar was chosen is because it was the last month of the Hebrew calendar in biblical times, marking the end of winter and ushering the month of Nissan, the first month of the new year. In the time of the Mishnah the rabbis changed the Hebrew calendar and declared that the year begins in the fall and not in the spring, but ibur ha-shannah stayed in its place (Rosh Ha-Shannah1:1).
There are a few expressions in Hebrew where ibur is used. For example, ibur ha-chodesh 'intercalary month' is the month where a day is added to the month (P'sachim 4:9) and sod ha-ibur literally 'the secret of intercalation' points to the knowledge of the adjustment system itself (Rosh Ha-Shanna 20). We should also mention the phrases Iburah shel ir 'a city sprawl', 'the suburbs' (Nedarim 7:8) and ibur din 'transgression of the law (Sh'mot Raba 30).
The consequence of having two months of Adar in a shannah me-u-be-ret is that the celebration of Purim is doubled. That is to say, in a leap year Purim is celebrated once as Purim Katan namely 'small Purim' on the fourteenth day of the first Adar and then it is celebrated in a big way on the fourteenth day of the second Adar (Megilah 6b). There are no specific instructions for the observation of Purim Katan but the fact that one does not mourn or fast on this date. A more festive meal is eaten but the Megilah is not being read.
In the spirit of Adar, the month that according to Jewish tradition always ushers simcha (Ta-a-nit 29:1), whether Purim Katan or Purim, I wish all our readers a fun and joyful holiday.
Professor Rachel Zohar Dulin teaches Hebrew and Bible at Spertus Institute for Jewish Learning and Leadership.