Purim has its specific mitzvos, or commandments, just like any other holiday.  The first of these is the public reading of the Book of Esther, the megillah.  This way the miracles of Purim are publicized and passed on from generation to generation.  Each year we again celebrate the downfall of our arch-enemy, Haman.  Each year we again give thanks to Heaven for rescuing us from his plot to annihilate the entire nation.

Our Sages added another three mitzvos specifically for this day of rejoicing.  We are enjoined to partake of a lavish Purim banquet, to send mishlo'ach monos - a present consisting of at least two types of food, ready to be eaten, to another Jew - and to give monetary gifts to the poor.

The festive meal is an obvious way of celebrating, but why do we first send presents to others, and give money to the needy?

In the megillah, we learn how Haman was promoted to the position of head minister, and proceeded to use his new power against the Jews.  Once installed in his new office, he worked to persuade his sovereign, Ahasuerus, to eliminate the people of Israel from the map of the known world.

And Haman said unto king Ahashverush: 'There is a certain people scattered abroad and dispersed among the peoples in all the provinces of your kingdom; and their laws are diverse from those of every people; neither do they keep the king's laws; therefore it does not profit the king to tolerate them."

In trying to fan the king's animosity against the Jews, Haman cited the fact that they were not a united community, but "scattered and dispersed among the nations…"  Haman attributed the survival of the Jewish people to their united front.  He sensed that over the years in the Persian exile, this quality had diminished; he hinted to this fact by stressing to the king that the Jews were no longer a cohesive community, but scattered and fragmented.  Consequently, this was the ideal time to eliminate them from the scene permanently.

The strength of a united Jewish people does not depend on their political situation.  The Jews are not united merely by political dominion over a common piece of real estate.  As centuries of exile have proven, Jews identify with, sympathize and fraternize with other Jews, regardless of their geographic location, language, or background.

A classic example is the Polish Jew, exiled to Russia during World War II, who roamed a marketplace in Buchara, looking for a fellow Jew.  At the time, the market was teeming with refugees from European countries, many of whom spoke only their native tongues.  Our friend went from one vendor to the next, as if to inquire about the merchandise laid out in array at his feet.  But instead of a question in his native Polish, he declared to each one: "Shema Yisroel …− Hear, O Israel …", the ancient declaration of Jewish faith.

After several attempts, one vendor jumped up to his feet, hugged the Polish Jew, and completed his words: "the L-rd is our G-d, the L-rd is one."

Although the backgrounds of the two were different in the extreme, and the only language they had in common was the Aramaic of the Talmud, the refugee found a warm welcome in the home of this Jew from Buchara, and spent the rest of the war years as his guest.

This was no isolated event, but a typically reaction of one Jew to another, 1,900 years after we lost our territorial sovereignty and went into exile.  It is a known fact that Jews help fellow Jews, no matter how fiercely they may disagree with them.  Even Haman, in his time, referred to us as "one nation…" despite the fact that they were scattered throughout Ahasuerus' vast kingdom.

However, in another sense, the unity of Am Yisrael was indeed under threat at the time of the Purim story.  The Jewish nation was born to serve as a vehicle to make its faith in G-d known to all the families of the earth.  This goal stands above all, and should unite Jews living throughout the Diaspora, regardless of the culture or language of their host country.  At the time of Haman, our dedication to this goal slackened.  So too, did the degree of unity among us.

The threat of genocide posed by Haman's plan to eliminate the Jews brought a wave of repentance, unity, and renewed dedication to our national goal.  The Jewish people renewed their allegiance to G-d and the mission He assigned them in this world. 

Differences of opinion among Jews is a proverbial phenomenon, as the quip goes: "Two Jews, three synagogues."  However, on Purim, these differences were put into their correct proportion; they became secondary to the unity engendered by the nation's miraculous rescue from annihilation.

One of the lessons of the megillah is the continuous need to cultivate this sense of unity among the Jewish people.  When we join hands to accomplish our mission in this world, we demonstrate that just as Israel is one, so, too, is Israel's G-d One.   In the merit of our national harmony, G-d will continue to protect us and redeem us from the countless enemies who would harm us.

This is one reason that Purim is celebrated with mitzvos that foster goodwill among fellow Jews: providing for the needy, to gladden their hearts, and exchanging gifts with friends and neighbors.  First we ensure that no one is in need; then we strengthen our bond of unity with those close to us.  And lastly, together, we sit down to a festive meal and rejoice that our King, who has called us to His service, rescued us in ancient Susa, and continues to rescue us throughout the ages.