In memory of my mother Esther Miriam Frimer
The source of the Fast of Esther (Ta'anit Esther) is somewhat obscure, particularly since it merits no explicit mention in the Talmud. In this short article, we will focus on three general approaches regarding the underlying reason for this fast.
1) The most common explanation views Ta'anit Esther as commemoration of a similar fast conducted during the time of Mordechai and Esther. But even within this general position we find two differing views. The leading Tosafist Rabbi Jacob ben Meir (1100-1171), Rashi's grandson, best known as Rabbenu Tam (the "Straightforward"), claims that this fast, observed the day preceding Purim, commemorates the fast conducted on that same day in Esther's time. Although the Megilla makes no reference to such a fast, Rabbenu Tam presumes that the Jews in Esther's time fasted on the thirteenth because it was the day they waged war against their intended executioners. As wartime warrants fasting and prayer, it stands to reason that the Jews engaged in just that on the fateful day of the thirteenth of Adar. This view is also cited by Rosh and Ran in the beginning of their commentaries to Masekhet Megilla. Maimonides (Hilkhot Ta'anit 5:5), by contrast, views this fast as recalling the fast observed "during the days of Haman", an apparent reference to the three-day fast ordained by Queen Esther and conducted in Shushan after the issuance of Haman's decree.
2) Rabbi Yosef Karo, author of the Shulhan Arukh, composed a work called Maggid Meisharim in which he posits that this fast was instituted out of concern for inappropriate conduct that may result from the levity and celebrations on Purim. A solemn fast day prior to the festivities helps guard one from sin on Purim day itself.
3) In a contemporary work of responsa entitled Resp. Shevet Hakehati, Rabbi Shammai Kehat Gross cites a fascinating approach to the fast posited by Kabbalistic thought. The Kabbalists suggest that because of the repentance of the Jews and the mercy of Heaven, Haman's decree was annulled; but there was no guarantee that Jews would escape such tribulations in future generations. Therefore, we, observe a day of fasting and prayer to beg for the final elimination of all future plots against us. Having repented, we can enter the Purim holiday confident of G-d's protecting hand, just like he did in the time of Mordechai and Esther of old.
So may it be! Chag Purim sameah to one and all.
[Based on the related discussion of Rabbi David Silverberg; http://gush.net/archive/salt-chagim/purim.htm]
Rabbi Dr. Aryeh A. Frimer is the Ethel and David Resnick Emeritus Professor of Active Oxygen Chemistry at Bar Ilan University.