The Purim Meal
Eat, drink, and be merry is not without controversy.
Drinking alcohol is a traditional part of the seudah, the Purim meal. This article, which presents a traditional perspective on this custom, explains that drinking on Purim is not meant to be excessive. The custom is not without controversy, and many Jewish authorities--today as well as historical--frown on the use of alcohol as a central part of the Purim festivities. Reprinted with permission from Celebrate! The Complete Jewish Holiday Handbook (Jason Aronson).
Esther and Mordecai proclaimed that Purim was a time of feasting and merrymaking (Esther 9:17, 22). This ordinance developed into the special Purim meal, or seudah, which takes place during daylight hours on the holiday. It is a most appropriate way to commemorate our success against a decree to physically destroy us, since it gives pleasure to the body.
As a secular meal, it does not include a kiddush (blessing over wine), except perhaps for a nonsense parody version, but nonetheless encourages partaking of plenty of wine. In fact, the most notable feature of the Purim seudah is the injunction, uncharacteristic among Jews, to drink until you don't know (ad lo yada) the difference between barukh Mordekhai v'arur Haman (blessed be Mordecai and cursed be Haman).
This is not an invitation to drink uncontrollably, but a way to recognize your limit. Once you reach the point of confusion, stop. (You are responsible for any damage caused by merrymaking and intoxication!) You are not supposed to get rip-roaring drunk on Purim, but happily tipsy. Not only does wine add to frivolity, it highlights the theme of drinking and how it helped create the miracle, throughout the Purim story. The saga opens with a series of wine-infused banquets (Esther 1:1-9), Esther's coronation is celebrated with a banquet (2:18), the Jews' fate is sealed with a banquet between Ahasuerus and Haman (3:15), Esther hosts two banquets for the king and Haman (5:6, 6:7), and the book ends with the Jews celebrating and agreeing to annually celebrate with feasts (9:17-19).
But why imbibe ad loyada? It seems to be a very strange notion in a religion that stresses remembering and making choices between different values. The formula may have been derived from a liturgical poem of talmudic times whose alternate verses ended "cursed…" and "blessed…" Only one who was sober could keep the rhymes straight. Another possibility is that since the gematria [numerical value of the Hebrew letters] of both phrases is 502, the two equal each other, and when you're drunk you can no longer prove this.