From the teachings of the Lubavitcher Rebbe; adapted by Yehoshua Metzinger
When the archenemy of the Jews, Haman, was drawing lots for an opportune time to wage his personal war against the Jews, he was delighted that the date of the deadly decree fell in the month of Adar. The reason he was so happy was that he found that every other month on the Jewish calendar had some auspicious date to aid the Jewish people, but in Adar he saw that Moses passed away on the 7th. Haman was so sure that this date would cause misfortune for the Jewish people that he made Adar the deadline for the decree.What are the special qualities of Adar that grant the Jewish people good fortune…?
However, what Haman didn't know is that Moses was also born on the 7th of Adar, which made the month an auspicious one for the Jewish people, not only during the events of Purim but also today. How did the joy of Moses' birthday cancel out the misfortune that the 7th was also the day of his passing, and what are the special qualities of Adar that grant the Jewish people good fortune?
Adar is under the constellation of the fish. Haman saw nothing particularly lucky or beneficial in the constellation of the fish. He was threatening to swallow up the Jewish people like a fish swallows food. But he didn't see that there was a bigger fish, and that he would be swallowed up himself. Just as larger fish swallow smaller fish, so the tragedy of Moses' passing is swallowed up by his birth, for that joy is greater than the sadness of mourning.
The mazal…and the soul are in perfect alignment on that day…
How do we know this is so? The Lubavitcher Rebbe points out that a person's soul shines stronger on his or her birthday. The aspect of the soul that is contained within a person is actually a spark of the person's root Neshama, which stays above. This Neshama that is above the earthly Neshama is called "mazal". A person's mazal is stronger on the birthday because the mazal, which drips vitality into the soul, and the soul are in perfect alignment on that day.
Even though we all individually have birthdays, Moses's birthday is like the collective birthday of the Jewish people. How is this so? Because the leader of the Jewish people is equal to the Jewish people collectively. [Num. 21:21, Rashi] Since every generation has a spark of the soul of Moses, his birthday is also the birth of the essence of the souls of the Jewish people. This is why the mazal of the Jewish people is stronger in Adar.
Adar is also the month of completion, rectifying the lunar year to the solar cycle and readying us for revelation. In leap years there are two Adars. In such a year, what was incomplete reaches its full potential. Just as the Jewish people are frequently compared to the moon, Adar is an auspicious time to reach one's spiritual potential.
Also, the two Adars together have 60 days. If an unkosher liquid falls into a pot, the mixture can still be considered kosher if the unkosher part is less than a ratio of 1/60. The 60 days of these two months reflect the ability of this number to nullify negativity.
But the sages have said that the Jewish people are beyond mazal and there is no ('ein' in Hebrew) constellation that is associated with them. This is why the Jewish people were able to show such self-sacrifice on Purim, and at all times; the capacity for self-sacrifice is beyond logic.
This greatness is hinted in the name of Adar which is spelled alef, dalet, reish. The alef represents the power of G‑d, which may seem to be separate from everyday existence. The dalet and reish form the word "dar", which means "to dwell". The alef, or G‑d's unlimited power, aims to create a dwelling place in this limited world.
Adar is a propitious month…for joy…
Moses tried to accomplish this in the last seven days of Adar when he worked to build the Tabernacle. The Shechinah wasn't revealed in the Tabernacle, so he kept rearranging and rebuilding it. Finally, on the last day, the Shechinah was revealed in the Tabernacle. The last seven days of Adar during which Moses spent building the Tabernacle correspond to the seven generations during which the Shechinah was not revealed. G‑d's intention was that he should have a dwelling place in this world, and this was being accomplished at the end of Adar.
Haman's mistake in thinking that Moses' passing ruined the month of Adar for the Jewish people was actually to our benefit; he chose to set the decree in the month of the greatest mazal for the Jewish people. This teaches us that Adar is a propitious month for protection, for improving ourselves and for joy, which reaches greater and greater levels as we progress through the two Adars.