We typically associate Purim with the other Yomim Tovim. The day has its own Mitzvos, customs, and rites like all the others. Yet if one looks at the Mitzvos of the day a bit closer, one sees how the nature of the day comes from a completely different source.
Take, for example, Seudas Purim. At first glance, this is like any other feast for Yom Tov. However, there are some differences. On a usual Yom Tov, the meal is eaten as the festival enters. The meal may or may not consist of bread, but must occur. Yet the Seuda of Purim has some qualifications which force us to reanalyze this comparison. Firstly, the Gemara Megillah (7b) says that one can’t fulfill his obligation of the meal at night. Secondly, we find that this meal is one of the three days on which one who is fasting all year must eat. Thirdly, though contested in the realm of Halacha, there is value of Chayav Inish Li’ivisumi, intoxication until one can’t see the difference between a Haman and a Mordechai. What do these Halachos tell us about the nature of the Seuda and our approach to Purim in general?
The Mishnas Ya’avitz has the following He’ara on the nature Purim which sheds light on our questions. When discussing the issue of Issur Melacha on Purim, the Megillah (see 5b) presents Purim initially as “Simcha, Mishteh, Yom Tov” (including Issur Melacha in the words “Yom Tov”) but concludes that there is only “Mishteh and Simcha” (leaving out Issur Melacha). Rav Dzolti points out that the Megillah’s concluding presentation of the order of names for Purim, Simcha then Mishteh, indicates the inner nature of the day. Initially, Purim was to be a holiday like any other Yom Tov, thus containing a proper Issur Melacha– highlighted by the first word “simcha”- like any other Simchas Yom Tov. However, the actual Chag was accepted by the people without a formalized Issur Melacha and the day took on a new form. Its focus became the Mishteh giving forth the Simcha.