The battles fought between the Jews and their enemies, which took place on Adar 13 throughout the Persian empire (see "Today in Jewish History" for that date), continued for two days -- Adar 13 and 14 -- in the capital city of Shushan, where there were a greater number of Jew haters. Thus the victory celebrations in Shushan were held on the 15th of Adar, and the observance of the festival of Purim was instituted for that day in Shushan and all walled cities. (See Laws and Customs below).
On this date, in the year following the Holy Temple’s destruction, G‑d tells Ezekiel to take up a lamentation for Pharaoh, king of Egypt, and for the Jewish nation’s other enemies, foretelling their ultimate downfall.
Read the prophecy here: Ezekiel ch. 32
In cities that are surrounded by a wall dating from the days of Joshua (13th century BCE) -- a prominent example is the city of Jerusalem -- the festival of Purim is observed on the 15th of Adar (instead of the 14th), in commemoration of the fact that in the ancient walled city of Shushan, the first Purim was celebrated on this day (see "Today in Jewish History").
All over the world, Tachanun is omitted due to the special joy of the day.
(For an overview of the Purim observances and links to more information, see "Laws and Customs" for Adar 14.)
How to unmask a blessing in disguise:
Stare it in the face and say, “I know you are not just a lousy day or bad luck. I know you are a good friend—even if for the life of me I cannot determine how. I know there is only one Source of All Things, and nothing can convince me that evil descends from Above. Evil descends from the constraints of my perception. You are no more than a blessing in disguise.”
This blessing, if truly a great one, will not surrender its cover easily. You will need a composure that demonstrates you meant every word you said. You will need to hold your ground like a mountain against the sea. You will need to surprise yourself with your own resolve.
And then you can turn over a world. A world that once distorted every blessing that squeezed through its gates will now open those gates wide. And the blessings that have already entered will sigh a breath of relief as one by one they discard their scary costumes.