What is unique about Purim in comparison with all of the other Yamim Tovim, is also what is unique about Megillas Esther in comparison with all the other twenty-three books of the Tanach. Our Sages state that in the future, after Mashiach comes, all the festivals, Pesach and Shavuos and Sukkos, will be nullified, though not Purim (and some say Chanukah as well), even though they are commanded by HaShem in the Torah, whereas Purim is not commanded in the Torah, but was instituted by the Anshei Knesses HaGedolah, the Men of the Great Assembly.

This must mean that the festivals will no longer be necessary. Whatever these Yamim Tovim achieve won't be relevant when Mashiach comes. Our Sages tell us that the same idea applies to the entire Tanach, excluding Megillas Esther.

The Rebbe asks how this can be possible, since other sources state that when Mashiach comes we will be able to fulfill all of those mitzvos which we are not able to do now, e.g., those associated with the Beis HaMikdash, such as sacrifices, and the laws of purity and impurity, etc. Moreover, the Rambam rules according to the latter view. The Rebbe gives two answers to this apparent contradiction. One answer is that the mitzvos will not be nullified in the first part of the era of Mashiach, but at a later stage. The second answer is that they will not be nullified in the sense that they will actually cease to exist, but in the same sense as a candle is not noticeable in the sunlight -- its light is nullified by comparison with a much brighter light. So, too, the light elicited by the other festivals will pale in comparison with that elicited by Purim (and maybe Chanukah).

However, whether we take it literally, or according to the Rebbe's second explanation, it is clear that there is something about Purim that transcends the idea of time. There's something eternal about Purim that makes it relevant forever. What is this eternal quality?

One of the laws in the Shulchan Aruch regarding the obligation of hearing the Megillah on Purim states that a person who read it lemafreiya did not fulfill his or her obligation. What does lemafreiya mean? The literal interpretation is that if a person heard the Megillah in the wrong order, the second half first, followed by the first half, for example, they did not fulfill their obligation -- one must hear it from beginning to end, in that order. You know how it is. You started getting the kids dressed up in their Purim costumes early, so that you could get them to shul in good time, without having to rush. Well, nothing ever goes wrong, does it? So you came late, and they were already in the middle of the Megillah-reading. "Nu!" you say, "Not so terrible, I'll hear the second half now, and the first half later." Nope. To fulfill your obligation, you must hear the Megillah in the right order! First the first half, and then the second half. That is the explanation of lemafreiya in halachah.

The Baal Shem Tov gives another interpretation: If you read the Megillah as past history, as something that happened to Mordechai and Esther long ago, you have not fulfilled your obligation. Why? Because the story told by the Megillah is absolutely relevant to us here and now!

In order to understand how those events are relevant to us, we need a little explanation...

The essence of the story of Purim began many years before the times of Mordechai and Esther, Haman and Achashverosh. Purim really began not long after Bnei Yisrael had come out of Egypt. After all of the miracles which had taken place, all the nations of the world were afraid of the Jewish People -- all of the nations excluding Amalek. Chassidus explains that the numerical value (the gematria, for those of you who know the word) of the Hebrew word Amalek equals the gematria of the word safek -- doubt, skepticism. Amalek had also heard of the miracles which took place. But the Amalekite philosophers argued, "Come on, what are you talking about? G-d is interested in what goes on down here? Those weren't miracles. They were lucky coincidences!" And so they attacked the Jewish people, cooling down the fear of G-d and the dread that other nations had of us. Others too began to be skeptical about the miracles that had taken place...

In later generations, Amalek clothed himself in his descendant, the treacherous Haman, who demanded the total destruction of the Jewish people. And so, in every generation, there is an Amalek, a Mordechai and an Esther. That which cools down the enthusiasm to fulfill HaShem's will is none other than Amalek. You've most probably heard something like the following many times: "You're not going to eat only that kosher certification, are you? Come on. Don't be such a fanatic!" Or, after you have just come out of a shiur: "You're walking around with these books, just like a bochur in Yeshivah?" And then you say, "Maybe I am being too religious; maybe I should just cool it! Maybe I took this upon myself prematurely; maybe I'm not ready for it." And so you start questioning what you're about to do.

Amalek can come from many different places. From things that you read, from what people say, from you yourself. But the end result is all the same: "Come on, don't get so excited about Yiddishkeit." That's Amalek and you have to fight it. Because when you fight Amalek, you will be together with Mordechai and Esther! And when you win -- because you will win if you are determined to do so -- then you will get a taste of Purim as it will be revealed in the future.