Chazal state that on Purim, one should drink מרדכי לברוך המן ארור בין ידע דלא עד until he doesn’t know the difference between "cursed be Haman" and "blessed be Mordechai."
Reb Efraim Zalman Margulies zt’l of Brod (Yad Efraim on Shulchan Aruch 695) writes, “In a dream, it was explained that we drink on Purim to be joyous, as it states (Tehillim 104:15), לבב ישמח ויין אנוש, ‘Wine gladdens the heart of man’... So he can praise Hashem for the miracles with a full heart... One shouldn’t drink too much until his mind becomes foggy because then he won’t think about the miracles. When Chazal say one should drink ידע דלא עד, until he doesn’t know the difference between Mordechai and Haman, this means, עד ולא עד בכלל, that he must stop before he reaches that intoxicated state. He should drink and be happy, but if he drinks so much that he can’t differentiate between Mordechai and Haman, the purpose of drinking is lost. Chazal wanted the kind of drinking that leads to praising Hashem. When one's mind becomes confused, he won’t be able to praise Hashem for the miracles. This was my dream, and I thought about it in the morning and saw it was correct.”
The Ahavas Yisrael of Vizhnitz zy'a says that the roshei teivos of דעי לאד דע spells ידע, to know. The Ahavas Yisrael of Vizhnitz explains that this tells us that one must know his limits when he drinks. If his drinking results in him embarrassing or harming others or causes him to be lax with any of the mitzvos, it is time to stop.
Based on the dream and lesson mentioned above, we can explain that the roshei teivos of ידע hints that even when we drink, our goal is always to know what we are celebrating. If you lose focus of the miracles, you went too far.
The Gemara tells the story of Rabba and Reb Zeira, who ate a Purim meal together, and due to the drinking, Rabba killed Reb Zeira. Afterward, Rabba resurrected him with his tefillos. Reb Efraim Zalman Margulies zt’l (Yad Efraim) writes, “They weren’t cautious; they drank beyond their limits. This resulted in a סכנה, danger. Therefore, one must be cautious not to drink excessively. One should drink up to ידע דלא עד, but never actually get to that point.”
Chazal say, בפוריא לבסומי איניש חייב, “One is obligated to be happy with Purim.” They didn’t say ביין לבסומי to be happy with wine. The goal is not to become intoxicated with wine but to be happy with Purim and the miracles.
The Kol Bo writes, “One must become intoxicated on Purim, but he shouldn’t get drunk because that is forbidden. There is no greater sin than being drunk. Being drunk leads to shefichas damim (murder) and giluy arayos (adultery). Rather, one should drink a little more than usual so he will be happy. In his joyous mood, he should make the poor happy and console them. That is the proper way to be happy.”
Matteh Moshe writes that one must be cautious that drinking on Purim doesn’t cause him to be lax in any halachah, such as washing for bread, benching, or davening correctly. He concludes, “All those who rejoice and praise Hashem for the miracles Hashem performed for our forefathers, their children will be like them, and Hashem will grant them success in all their endeavors.”
Lev Ha’Ivri writes that the Rema (Reb Moshe Isserles zt’l) was niftar at the age of 33, on the 3rd day of the omer, and at his levayah, 32 praises were said. They were looking for one more praise to tell about the Rema so that the praises would equal 33, the same as the day of the omer and the years of his life. Someone came forward and said, “On Purim, the Rema would dress up (so people wouldn’t recognize that he is their Rav) and go from home to home to remind people to daven maariv.” That was the 33rd praise.
