Midrash Esther IV: Long Term Effects
The Rabbis said: Artaxerxes was the same as Achashveirosh, meaning Artaxerxes was the nickname; and why was he given this nickname? Because he used to fall into a passion and then be sorry. Some commentaries explain this final phrase in a different manner: he was called Artaxerxes because he would upset people and, by doing so, would weaken their resolve.
The Rabbis see Achashveirosh as his given name. They believe that his nickname Artaxerxes was given because of what happened in the story told in the Book of Esther. The Rabbis read the Book of Esther as the story of an established king who loses the respect of his people, either because of his volatile behavior, or because all he accomplished was to weaken the resolve of his subjects. The worst damage caused by Achashveirosh, was not his order to wipe out the Jews; it was that his reign lead to unstable times, and volatile times are always dangerous for the Jews.
It is not enough to read the Book of Esther as a story about the Jews. We must understand the political and social realities that resulted from this unstable King’s reign. This is not a story that ends with the Book of Esther; it is only the beginning of a story that continues throughout the Second Temple period and all that has since followed.
We are taught that Purim is an eternal holiday, meaning that all the lessons learned would last for ever. The Rabbis see Purim as the antithesis of Achashveirosh. They see Purim as a response to all the future generations who would live under volatile rulers and be desperate for some sense of stability and security. The Rabbis insisted that by learning the Purim story we would find the necessary resolve to live through even the most unstable times.