While the Fast of Esther is a day of solemnity, it isn't for me - it happens to coincide with my son Asher's brit mila - only the second to be held in the historic Eldridge Street Synagogue on Manhattan's Lower East Side in the last half- century. In fact, the 13th of the month of Adar, the date on which the Fast of Esther falls, boasts a distinguished history as a day both jubilant and mournful. During the early Maccabean era, the 13th of Adar was not the Fast of Esther, but the Feast of Nicanor - at the time one of the happiest holidays in the Jewish calendar. So who was this Nicanor, why did he merit such an illustrious feast, and were did it go? The First Book of Maccabees reports that not long after the events commemorating Hanukka, King Demetrius, nephew of Antiochus Epiphanes, dispatched his Jew-hating general Nicanor on a mission to slaughter Judah Maccabee and "The People" once and for all. The fateful battle between Judah and Nicanor took place on the 13th of Adar. Happily, things didn't turn out as planned: the Jews routed the army of Nicanor, who himself fell in the battle, his head placed in short order on public exhibit in Jerusalem. Nicanor's Day was decreed in the Second Book of Maccabees as a feast to celebrate this deliverance, and was widely observed in the Land of Israel over the next two centuries - until the destruction of the Temple. YET DESPITE its onetime prominence, this feast has vanished from our calendar. What then happened to Nicanor's day? Before addressing this question another must be settled: how could such a happy occasion be celebrated on the 13th of Adar in the first place? Wasn't this particular date in the Jewish calendar already taken, and by a well-known fast day at that? Apparently not. Until Maccabean times, neither Purim nor the fast that precedes it are mentioned anywhere outside of the Book of Esther (which Jewish tradition dates to the 5th century BCE, but was probably written around the time of the first Hanukka). In fact, it would be three centuries before the word "Purim" is first coined - in the Mishna. The single hint of an emergent proto-Purim is found in the aforementioned decree in the Book of Maccabees II, announcing the Feast of Nicanor on Adar 13th. The text notes that the feast falls one day before a certain "Mordecai Day," a previously unmentioned, but obvious precursor of Purim. It seems that the holiday later known as Purim arose in the long-established Babylonian/Persian Diaspora, as a Jewish adaptation of a Persian end-of-winter masquerade celebration, similar to Europe's Carnivale and Louisiana's Mardi Gras. One need look no further for the holiday's Babylonian roots than the names of its heroes: Mordecai is derived from the Babylonian god Marduk; as for Esther, Rabbi Nehemiah explains in tractate Megilla 13a as follows: "Hadassa was her original name; why then was she called Esther? Because Idol worshipers referred to her after the name of the planet Venus, or Ishtar." Since Mordecai Day was a holiday of the Mesopotamian and Persian Jews, it's not surprising that their brethren in the homeland didn't come around to adopting it for some time. After all, they already had their own established day of national deliverance in the form of Nicanor's Feast. The ambivalence of homeland Jews with respect to both Purim and the Book of Esther is suggested in the Talmud. Megilla 7a relates a mysterious tale in which the rabbis of Israel receive a letter from Queen Esther demanding that the rabbis accept - the text isn't clear which - Purim, her Megilla, or both. The rabbis of the Holy land hesitate, wondering aloud whether yet another festival that is sure to upset the gentiles is really necessary. Esther persists in her demands in the face of their resistance, declaring that the King of Persia himself has accepted her holiday. As it happens, the Talmud records the vigorous rabbinic debates on the merits of admitting the Book of Esther into the Biblical canon. Those rabbis that doubted the Megilla's sacred bonafides took issue with the total absence of God's name from the narrative as well as the spectacle of a Jewish maiden marrying a gentile king. But as we know, the Jews of Israel did ultimately adopt Purim, and the Megilla was finally allowed into the Biblical canon. WHICH BRINGS us to the fate of Nicanor Day. Two disastrous Jewish rebellions (in 66-70 and 132-135 CE) against Rome and a destroyed Temple would have rendered the jubilant Nicanor's feast outdated. Under the circumstances, a transformation of the 13th of Adar from Nicanor's jubilant feast into Esther's mournful fast would not have been unreasonable. With the old feast now a new fast, the Persian Mordecai Day was left to develop into Purim. That Esther's day replaced Nicanor's does make historical sense: after all, it was the Babylon-based rabbis who would ultimately gain halachic pre-eminence and leadership at the expense of their colleagues in the Land of Israel, deciding which holidays were or weren't observed. As far as I'm concerned, restoring the now sorrowful 13th of Adar to its original joyous character would suit me fine. I'll just call it Asher's Day. The writer is a New York-based author and research analyst. He is now writing a graphic novel about life and loss on the Lower East Side.