"When Adar arrives, we increase our joy." (Talmud Ta'anit 29a) The miracle of Purim teaches us that not everything that appears bad - is truly bad. A situation that appeared to spell doom and gloom, completely turned around. Not only was the evil threat negated, but "the exact opposite occurred, when the Jews ruled over their enemies." (Esther 9:1)
Initially, Haman's plan to exterminate the nation was approved and quickly gained steam; the Jews were in serious danger. It was only later, at a point at which it looked as if we were on the verge of being destroyed, only then, "did matters turn around completely, and the Jews ruled over their enemies".
The 180 degree turn of events constituted not only a physical, but also a spiritual, salvation. Prior to the miracle, the Jewish people faced a serious spiritual crisis, many having actually bowed down to idols. The Jews were assimilated, and, as our sages say - "partook of the meal of that evil one [King Achashverosh]" (Talmud Megillah 12a) Only later, after the miracle of Purim took place, did "they re-accept the Torah in the days of Achashverosh." (Talmud, Shabbat 88a) Purim brought about a voluntary receiving of the Torah, a turn of events that can only be described as an overwhelming spiritual re-awakening. The process reverberated to the broader society, and, as the Megillah itself (Esther 8:17) notes: "Many of the [non-Jewish] inhabitants thereupon converted to Judaism".
From the Purim story, we, the Jews, learned how to relate to reality in a different way. We began to understand how even the threat of total annihilation can be foiled and bring about a new national "lease on life." Indeed, a short time after the original Purim, our Holy Temple was rebuilt. A Daring plan
Just imagine the feelings of the Jewish people when Esther invited Haman and Achashverosh to her feast! The Jews were surely shocked - how could Esther dare invite those two characters to a party when her nation was on the verge of being exterminated? Why would she invite this evil man, the most wicked person of the time, a Jew hater, to her party? The next day it was even announced that there would be yet another feast, and that both Haman and Achashverosh were invited again!
In the end, it became clear that the invitation was, from the very beginning, designed to bring about the downfall of the wicked Haman. Only in this manner, through invitations to parties, was it possible to catch him off-guard; he never suspected Esther of any such plan, and was totally unprepared for what was to befall him.
Esther's successful strategy indicates that sometimes, meeting the enemy, attending parties with him, "dialoguing" with him, so to speak, is that which will bring him down, lead to his being hung on a tree on which he hoped to execute his enemy.
"When Adar arrives, we increase our joy." Everything is open, everything is fluid, everything can turn out for the best. "Salvation and redemption will reach the Jews from another source." "And the Jews experienced light and joy and happiness."