Reading the Megillah Out of Order
The Baal Shem Tov cites the Mishnah that states that "one who reads the Megillah backwards (or out of order) has not fulfilled their obligation" (הַקּוֹרֵא אֶת הַמְּגִילָּה לְמַפְרֵעַ לֹא יָצָא). With this, the Besht proclaimed, the lesson of the Mishnah is that one who views the story of the Megillah as something that occurred in the past and only has true significance for their ancesters and the past generations of Jews cannot fulfill their obligation.
(Keter Shem Tov, pp. 336-337 (Hosafot §100) - Kehot Edition)
Midrash - Esther Rabbah / The Experience of Exile
The Midrashic approach to the story of Purim is one that links the statements concerning Exile described in Sefer Devarim, the story of the Jews in Persia, and the experience of the Jews under Roman rule (i.e., before and after the destruction of Jerusalem).
And God will scatter you among all the peoples from one end of the earth to the other, and there you shall serve other gods, wood and stone, whom neither you nor your ancestors have experienced. Yet even among those nations you shall find no peace, nor shall your foot find a place to rest. And there God will give you an anguished heart and eyes that pine and a despondent spirit. The life you face shall be precarious; you shall be in terror, night and day, with no assurance of survival. In the morning you shall say, “If only it were evening!” and in the evening you shall say, “If only it were morning!”—because of what your heart shall dread and your eyes shall see. - (Devarim 28:64-67).
Megilat Esther begins with "Va'yehi" ("And it was") which is typically understood in the Talmud and Midrashic writings as an expression of woe ("va'y").
The Midrash introduces a debate between Rabbi Berakhia and the Sages on the theme of exile using a parable of three forms of food insecurity.
The Rabbis said: “Your life will be suspended before you,” that is one who purchases wheat for a year. “And you will fear night and day,” that is one who purchases wheat for himself from the retailer. “And you will not be assured of your life,” that is one who purchases for himself from the baker.
Rabbi Berekhya said: “Your life will be suspended before you,” that is one who purchases wheat for himself for three years. “And you will fear night and day,” that is one who purchases wheat for himself for one year. “And you will not be assured of your life,” that is one who purchases wheat for himself from the retailer.
The Rabbis objected to Rabbi Berekhya: What of the one who purchases from the baker? He said to them: The Torah did not speak of the dead.
Summary: For the Sages, these insecurities relate to the wholesale customer who buys one year's worth of wheat supply, the retail customer, and the bakery customer. The common theme here is that without land, these individuals are reliant on others for their food supply. For Rabbi Berakhia, these insecurities relate to the wholesale customer who buys three years' worth of wheat supply, the wholesale customer who buys one year's worth of wheat, and the retail customer. Rabbi Berakhia views the bakery customer as a "deadman" who has no hope for food security.
Another interpretation: “your life will be suspended before you,” that is one who is placed in the prisons of Caesarea. “And you will fear night and day,” that is one who is taken to judgment. “And you will not be assured of your life,” that is one who is taken out to be hanged.
Rav interpreted the verse as relating to Haman: “Your life will be suspended before you,” – on the day following the removal of the ring. “And you will fear night and day” – when the letters were dispatched. “And you will not be assured of your life” – “to be ready for that day” (Esther 3:14).
For Rav, these threat levels are reflected in the Purim story, as the threat of destruction becomes more certain, the terror on the part of the Jews keeps increasing.
From the Political to the Personal
The Baal Shem Tov's approach to the Megillah story is to read personal spiritual struggles into the text. Below are two examples.
The Common One Rushes to the Front
The Baal Shem Tov taught that humility is essential for serving God, connecting the biblical injunction against using leaven or honey in the Mincha sacrifice (seor u'devash) (see Leviticus 2:11, cited below) with the Talmudic teaching that the "common man rushes to the front", meaning, the one of little merit and stature (katan) seeks to be present themself as one of great merit and stature (gadol). Leaven and honey cause food to rise and appear prominent thereby symbolising a lack of humility, and so, these ingredients were excluded from the sacrifice.
(Keter Shem Tov, p. 239-240 (§393) - Kehot Edition)
The Queen's Distress
The Baal Shem Tov reportedly was asked by his student what should be done if one senses that one's "bowels begin to feel loosened" during prayer and meditation. The Baal Shem Tov's response: One should make the effort to persevere in prayer and use that moment to reflect on the lowliness of the human. Just as these human needs are described in terms of small [needs] (ketanim) and great [needs] (gedolim), these refer to the ubiquity of human small-mindedness and the need for the spiritual seeker to discover an expanded state of consciousness. And this is the deeper meaning of the Talmudic passage that the inner distress and turmoil of Queen Esther related to the "loosening of the bowels".
(Keter Shem Tov, p. 177 (§303) - Kehot Edition)
Linking the Midrash and the Chasidic Approach
The Price of Barley
The Midrash describes the encounter between Haman and Mordekhai (right before Mordekhai's parade)
“Take the garments and the horse… Haman took the garments and the horse.” He went to Mordekhai. When [Mordekhai] was told that [Haman] was coming, he was very afraid, and he was sitting with his students before him. He said to his students: ‘My children, run and remove yourselves from here that you are not burned with my coal, as the wicked Haman is coming to kill me.’ They said: ‘If you die, we will die with you.’ He said to them: ‘If so, let us stand in prayer and pass away while praying.’ They completed their prayers and sat and engaged in the Halakhot of Sefirat ha-Omer, as that day was the 16th of Nisan and on that day they would bring the Omer offering at the time when the Temple stood. Haman came to them and said to them: ‘What are you engaged in?’ They said to him: ‘In the commandment of the Omer. That is what it says: “And if you present an offering of the first fruits to the Lord…”’ (Leviticus 2:14). There they say: They showed him the Halakhot of taking a handful [of a meal offering]. And [these interpretations] are one and the same, as they would take a handful from the omer. He said to them: ‘This omer, what is it? Is it [made] of gold or of silver?’ They said to him: ‘Not of gold and not of silver and not of wheat, but of barley.’ He said to them: ‘What is its value? Is it ten kantrin?’ They said to him: ‘It goes for ten manin.’ He said to them: ‘Rise, for your ten manin have vanquished my ten thousand kantrin of silver.’
A possible Chasidic interpretation: Even "small mitzvot" (a handful of barley, worth a few cents), if performed with the correct intention and spirit, may be greater than a grand, ego-filled display of purported righteousness.