His recent lecture Megillat Esther and its Hidden Message is quite interesting, as it points out many of the metaphorical qualities of that sefer. The story takes place after the Babylonian exile when the Jews - under Koresh (Cyrus) and later Daryavesh (Darius) - had the opportunity to return to the land of Israel. R. Leibtag is somewhat schizophrenic in this matter, because he quotes Seder Olam - the majority opinion in Chazal [and which today only OrthoFundies believe is accurate regarding the Persian period] - "that Achashverosh was the Persian King immediately after Koresh, but before Daryavesh", but his thesis seems to focus primarily on what the majority of historians believe (and a minority opinion in Chazal), that Achashverosh [Xerxes] succeeded Darius. Thus the story of the Megilla takes place some forty years after the Second Temple was built, after Chagai & Zecharia's plea to return and fulfill the potential of the Temple.
Achashverosh reigned after Yirhimyahu's prophecy of seventy years of exile had been completed. However, as mentioned in Ezra/Nechemiah, only about forty thousand Jews returned and the majority stayed in Bavel. Because they did not take heed to Zechariah's message, the later generations were found scattered all over the Persian Empire in the Megillah story. The story is written as a "satire" that shows how the Jews of Persian had replaced the Temple with Shushan. Some of the points that R. Leibtag musters to support this theme:
- the "ish yehudi" should have been in the "bira" in Yerushalayim, making God's Name known to other nations; instead, the Megilla opens as an ish yehudi in the bira of Achashverosh in Shushan, ironically with the name of a foreign god (Mordechai=Marduk).
- Vashti refuses to appear before the King who therefore becomes angry; similarly the Jewish people did not respond to its divine call and so God becomes angry (the Jewish nation is often compared to God's wife)
- the Jews replace the bet ha-mikdash with the palace of Achashverosh. Examples:
- the word bira is used to describe Shushan. The only other time in Tanach where this word is mentioned, bira describes specifically the bet ha-mikdash (Divrei Hayamim).
- the Jews at the party are using the vessels of the Temple according to Chazal.
- the gemara (Megilla 12a) claims that Achashverosh donned the garments of the kohen gadol at his party.
- entry to the inner chamber of the king's palace is forbidden under threat of death; this parallels the Holy of Holies in the mikdash (Purim / kippurim).
- the 'waiting area' outside the inner chamber is called the chatzer ha-chitzona where those close to the King - like Haman himself - are allowed to enter freely; this parallels the kodesh where kohanim are permitted to enter.
- in front of the palace is gate of the palace where people like Mordechai are permitted to stand; this parallels the azara in the Temple.
- Haman's petition to Achashverosh to destroy Am Yisrael echoes God's threat in Shirat Ha'azinu to destroy the Jewish people for not keeping His laws
- Israel's salvation from Haman's decree comes only after a three day fast during the holiday of Pesach, a holiday that represents freedom from subjugation to a foreign nation
- special mitzvot are instituted to respond to Zecharya's messages of helping the needy (matanot le'evyonim) and acting properly towards one's neighbors (mishloach manot).
R. Leibtag then shows a connection between Yirmiyahu's prophecy of seventy years and the 70 days between the sending of the original decree calling for the destruction of the Jews and the one calling for its repeal. "During these seventy days, the Jews throughout the Persian empire thought their doom inevitable, an ironic reminder that they had not heeded Yirmiyahu's prophecy of what he expected from Bnei Yisrael once the seventy years had expired."
I encourage you to read the entire shiur as R. Leibtag develops these ideas in much greater detail.
For me, one of the most interesting parts of the shiur is this parenthetical statement: "Before we continue, it is important to clarify a problematic issue. We are about to relate many elements in the story of the Megilla to a satiric commentary on Persian Jewry. This does not mean that these events did not actually occur. The story of the Megilla is true and based on historic facts. However, its prophetic message is conveyed through the use of literary tools, such as satire and irony."
I don't believe that R. Leibtag can muster any evidence whatsoever for his statement that the story "is true and based on historic facts" other than the oft-used claim of last resort - "we have a mesorah!" But his compelling analysis does give us a greater understanding for why this inspiring, yet largely fictional, story was written.