Shabbos Zachor (March 12):

The Shabbos immediately preceding the festival of Purim is called Shabbos Zachor ('Remember'). In the Torah reading service, we read the command in Deuteronomy 25:17–19 that begins "Remember what Amalek did to you…", and ends by saying, "…you shall blot out the remembrance of Amalek from under the heavens: you shall not forget!" In order to fulfill this commandment of remembrance, we read this passage aloud once every year, on the Shabbos before Purim, since the villain of the Purim story was Haman, who was of the offspring of Amalek. Everyone should make an effort to hear this passage being read.

Amalek's enmity toward Israel was more than just opportunism. It stemmed from a total antithesis of belief, since Israel proclaimed the sovereignty of G-d, and Amalek believed in no god but the power of random chance and the survival of the fittest. Amalek is not an ethnicity or racial group, but an ideology; and the banner of Amalek seems to have no shortage of people who wish to adopt it: the philosophy of atheistic evolutionism, materialism, and a belief that 'might makes right'. Therefore, Amalek and all those who follow its ideology are eternal foes of G-d and His Torah, and must be opposed in every generation. "And Hashem said unto Moses, Write this for a memorial in a book… that I will utterly blot out the remembrance of Amalek from under the heavens. … Hashem will have war with Amalek from generation to generation." (Exodus 17:14,16)

In the haftarah (reading from the prophets) associated with this passage (I Samuel 15), King Saul was told to destroy Amalek, but he disobeyed the command of G-d, and left Agag king of Amalek alive. From this failure would eventually come Haman the Agagite, who would threaten Saul's own descendants, Mordechai and Esther.

Ta’anis Esther: Adar 13 (March 16)

The 13th of Adar was the day scheduled by royal decree for the total annihilation of the Jews. Upon hearing of the decree, Esther requested that the Jewish people fast for three days, asking G-d for mercy as Esther prepared to go before the king to beg for the life of her people. (This original fasting took place in the month of Nisan, not in Adar itself.)

Since the days of Esther, to commemorate this period of fasting and repentance, we fast for a single day, from sunup to sundown, on the anniversary of the dreaded date of extermination. Yet we do not fast out of fear; when that day finally arrived, the Jews fought back and were given victory over their enemies who assembled to destroy them. That day of fighting is another reason for fasting on this day. We do not take pleasure in shedding blood – we only rejoice in our own survival in the face of all odds.

This year, let us remember those who are fighting for their lives and homes, and fast and pray for their miraculous deliverance as well.

Purim: Adar 14 (March 17)

This day commemorates the relief and celebration after the Jews had victory over their enemies. Rejoicing and merrymaking is the order of the day. Jews everywhere gather for parties at which costumes (disguises) are worn, to remind us of the veiled and disguised acts of G-d which brought about the redemption. The Megillah (Scroll) of Esther is read publicly. Children are encouraged to make noise when Haman's full name is read in order to 'blot it out' – within the bounds of reason, and taking into account the delicate eardrums of their elders!

We make portions of food to send to one another, and charity to the poor on this day is especially unbounded and open-ended: we do not try to distinguish whether a needy person is being genuine in describing their plight, or whether we might be giving to a scam artist and professional 'beggar'. On Purim, G-d saved us with an 'irrational' generosity, regardless of whether we were worthy or pious or had done anything at all to earn it, so we should likewise refrain from asking probing questions of anyone who asks us for something on Purim, and we should simply give freely, as we have received.

Shushan Purim: Adar 15 (March 18)

Since the Jews of the capital city of Shushan fought for an additional day, they celebrated their rest and relief a day later than everywhere else. Therefore, the 15th of Adar is also kept as a second day of rejoicing, to be observed by residents of ancient walled cities (today, this second day is only observed in Jerusalem).

(Megilla 7b)

First, it is important to note that the passage in the Gemara does not say anything specifically about drinking or alcohol, or even intoxication. It says that a man is required to "mellow himself" (literally, to "sweeten himself"). The word is besomei. It comes from the root besem which means "sweet" or "aromatic". Besem is also the root of besamim, spices. The literal understanding of the passage might then emphasize an enjoyment of any kind, whether in food, drink or other amusements, rather than being an instruction to get sloshed.

Second, even if the idea of drinking is implied here, those rabbis who have commented on this passage have all taken it in a non-literal sense. R' Aryeh Winter quotes some of them:

"The Chafetz Chayim writes [that you should drink] until you cannot differentiate between the good things that Hashem has done for us - the downfall of Haman and the victory of Mordechai … The Chayei Adam writes that if one knows that he will not act properly or even not say the Grace After the Meal properly, he should not drink. The Chafetz Chayim writes that the preferred method of fulfilling the directive of the Gemora is to drink a little, and then take a short nap [since while sleeping, one cannot tell the difference between Haman and Mordechai.]"

(from "Megillas Esther Part XI - A Celebration for Generations", published by R' Y. Prero)

Rabbi Yehudah Prero concurs, and also finds significance in the exact wording of the instruction:

"Punishments, downfalls, and failures tend to stand out in the public eye. People take note when someone who had been so successful, so politically savvy, so wealthy, fails miserably. The punishment, the "vengeance" of G-d taken against those who dare to defy Him, is noticed when it occurs.

However, when the righteous live in tranquility, when the upright succeed, it rarely makes the headlines. Those who understand how G-d works recognize that in such situations, the success is G-d's way of rewarding those who listen to Him. However, the reward is often not appreciated for what it truly is: the hand of G-d in action.

…If a person does indeed celebrate, by feasting and drinking, keeping these two events in their proper perspective, they are feasting properly, "for the sake of heaven." However, as soon as one begins to celebrate Mordechai's success more than Haman's decline, they have reached a point where they have lost the proper perspective. This rejoicing can no longer be categorized as being solely for the sake of heaven.

…“The Vilna Gaon explains this to mean 'until one can no longer tell the difference between the vengeance taken out on Haman and the rise in fortune of Mordechai.' … [However,] we should drink only until the point where we won't be able to differentiate between the revenge exacted on Haman and the rise of Mordechai. Once we have blurred events and their corresponding significance, we are no longer acting in the true spirit of Purim. We are told we should drink "until" that point. We may drink as long as we rejoice with the proper mindset. However, we cannot cross that line. We should not reach the level where we can no longer differentiate between the significance of the two occurrences. That is the instruction, the warning of the [Gemara]."

(from "Knowing Why and When To Say When", adapted from Sefer Kimu V'Kiblu)

In other words, Rabbi Prero sees the Gemara's instruction as a warning against over-imbibing, not as license to do so. A man may think he can take a certain amount and remain 'relatively' sober, but the rabbinic injunction forbids a man to allow enjoyment of the day to cloud his thought processes.

But even if this is the case, why does the Gemara choose to use such an extreme example as a boundary line that may not be crossed? Surely it would make more sense to forbid intoxication to a much lesser degree than a failure to distinguish between the rise of the Purim hero and the fall of the villain!