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 regular years, the 15th of Adar is Shushan Purim, the festival that celebrates -- in Jerusalem and other ancient walled cities -- the salvation of the Jewish people from Haman's evil decree in the year 3405 from creation (356 BCE). In a leap year -- which has two Adars -- Shushan Purim is observed in Adar II, and the 15th of Adar I is designated as Shushan Purim Kattan, the "Minor Shushan Purim."
There are no special observances associated with Shushan Purim Kattan, other than the omission of Tachnun ("supplications") from the daily prayers and a prohibition against fasting or holding eulogies on this day. The Code of Jewish Law cites an opinion that one should increase in festivity and joy, but rules that there is no obligation to do so; "Nevertheless,a person should increase somewhat in festivity... for 'One who is of good heart is festive always' " (Shulchan Aruch, Orach Chaim 697:1).
To one whose self is his body, death of the body is death of the self. But for one whose self is his love, awe and faith, there is no death, only a passing. From a state of confinement in the body, he makes the passage to liberation. He continues to work within this world, and even more so than before.
The Talmud says that Jacob, our father, never died. Moses, also, never died. Neither did Rabbi Judah the Prince. They were very high souls who were one with Truth in an ultimate bond—and since Truth can never die, neither could they.
Yes, in our eyes we see death. A body is buried in the ground, and we must mourn the loss. But this is only part of the falseness of our world. In the World of Truth, they are still here as before.
And the proof: We are still here. For if these high souls would not be with us in our world, all that we know would cease to exist.