"We fast on the thirteenth of Adar, on Taanis Esther." These are the opening words of HaRav Shlomoh.
We fast then, as is stated in the Mishna Berurah. Because in the times of Mordechai and Esther, they [the Jews] congregated on the thirteenth of Adar to fight for their lives and had to seek mercy and compassion which would stand them by in seeking revenge from their enemies. We find that when they fought, they did so through fasting.
This is why is it is customary to fast on the thirteenth of Adar, which is called 'the fast of Esther' to commemorate that Hashem sees and harkens to every individual in his plight when he fasts and returns to Hashem with his whole heart, as they did in those times.
We must understand why it is necessary to make a remembrance of this fasting which was coupled with prayer for all times. The central event was the miracle which was performed for Jewry's redemption. What was so significant about this that it be commemorated for all coming generations, outside of the days of Purim themselves?
Another thing which we must understand is that on Chanukah, the righteous Chashmonaim also designated a fast day when they went forth into battle against the Greek empire. Why was not such a day also established as a national fast day for all coming generations?
In order to understand this, an additional fact must be understood which makes Purim outstanding. This is the fact that we are joyous from the very beginning of the month. We find no other festival which behooves us to be joyful from the very onset of the month.
HaRav Shlomo provides an answer which he heard from his father, HaRav Chaim Kanievsky, which he said very succinctly as was his custom: "The miracle of the days of Purim was the only miracle of the many, which we commemorate as having taken place after the Churban."
HaRav Shlomo explains: Up until the Churban, Hashem's Divine Providence with the Jewish People was direct and palpable, beginning with the overt and amazing miracles taking place with the exodus from Egypt up to and including those miracles which took place in the Beis Hamikdash itself on a daily basis.
In the period of such obvious and open Divine Conduct, there is no major difference between the extraordinary miracles which took place regularly or even singularly at different times, which is why there is no special designation or commemoration of joy thereof from the beginning of the month when they occurred.
The miracle of Purim, of Esther, however, took place after the First Churban, a period of concealed Divine Conduct. Similarly, those events related in the Megilloh itself, were not outstanding from normal or natural circumstances which characterized that period.
It was quite logical that Achashverosh hold a feast to demonstrate his wealth. Similarly, that in his drunkenness he issue irrational commands regarding Vashti. It was quite conceivable that the king empower one of his ministers whom he favored and that this selfsame anti-Semite seek to bring about the total genocide of the Jews. After all, in the course of history, we have encountered, not one but many, who sought to exterminate the Jewish people, and whose wildest dream was similar to that of the wicked Haman. We recognize such elements today as well.
If we look at the events of the Megillah at face value, without the additions of Chazal, everything seems like a normal sequence of events. It displays hashgocho protis but nothing supernatural.
Nonetheless, Chazal teach us that the events were really full of numerous miracles. Purim teaches us that even in a period of hester ponim Hashem loves us.
