Purim, 5773, officially began Saturday evening as the Megillah of Esther is being read in hundreds of synagogues in Israel alone. The holiday celebrates the defeat of one of Israel’s worst enemies, Haman the Wicked, in ancient Persia.

In Jerusalem, the Purim celebration will only begin Sunday evening. This has to do with the fact that Jerusalem was surrounded by walls from the time of the conquest of the Land of Israel by Joshua. Jewish tradition has it that Jews in the walled city of Shushan – the capital of ancient Persia – fought against their enemies for an extra day before defeating them, and therefore people living in walled cities begin celebrating Purim a day later than others.

Not many know that the holiday associated with children’s costumes and revelry is one of Judaism’s most holy days. It is considered to have great spiritual significance, and the Book of Zohar connects between the name of Yom Kippur, which is also known as Yom HaKippurim, with Purim.

The Jewish sages in the Biblical midrashim, or expositions, go so far as to predict that when the Messiah comes, all of the holidays will be cancelled except for Purim as the Scroll of Esther says that the memory of those days will remain with the Jewish people forever.

There are four commandments (mitzvahs) on Purim: hearing the Megillah twice (that includes women, as they, too, were in danger of being killed by Haman); sending a gift of two kinds of ready-to-eat foods to a friend (shalach manos in Yiddish, mishloach manot in Hebrew); giving alms to at least two poor people, as well as eating a festive meal, which involves drinking and being merry, before dark.

Rabbi Eliezer Melamed, the Rabbi of Har Bracha, explains that while Jews are commanded to drink and be merry on the holidays of Sukkot, Pesach and Shavuot as well, Purim is different in that there is an express mitzvah to drink to the point of not differentiating between Haman and Mordechai, which some take as a license to becme drunk.  The chief rabbi of Holon, Rabbi Avraham Yosef, son of Rabbi Ovadia Yosef, emphasized on Friday on Israel’s Radio Kol Hai, that what is mandatory is drinking to be happy, rather than becoming drunk.

Every Jewish man is are expected to drink on the holiday, and this must be done in the daytime, because the Megillah says that Jews held “days of drinking and happiness” to celebrate their victory and escape from the jaws of destruction. While Jews are not known in general as heavy drinkers, Purim is definitely an exception to this rule, and visitors walking down the street in religious neighborhoods will not only hear music blasting from every corner and see masses of happy, costumed children and families delivering mishloach manot, but also notice inebriated, staggering  yeshiva students.

Since the Purim story seemed to be a series of coincidental natural events, it is termed a “hidden miracle”, and it is customary to eat foods have something hidden in them at the festive meal, such as stuffed cabbage rolls, kreplach (Jewish ravioli filled with chicken or meat) and filled hamantaschen cookies. These are known as ozney haman, or Haman’s ears, in Hebrew.

Masquerading on Purim is another way to symbolize the hidden aspect of the holiday and the fact that Esther did not tell the king her Jewish origins till the end of the story.

Another principle expressed in Purim is expressed by the phrase “nahafoch hu” – which can be translated as “the opposite took place” – and which appears in the Megillah to describe the fact that while the Jews’ enemies had prepared to slaughter them, the opposite happened and the Jews wound up slaughtering their enemies.

(For details on the mitzvahs of Purim, click here. For Torah essays on the holiday, see Arutz Sheva’s Judaism section.)