A teaching by Yehuda Leib Alter of Ger, from Sfas Emes, on Purim.
It is written in the Gemara that we are obligated to become so intoxicated on Purim that we cannot tell the difference between “Blessed is Mordechai” and “Cursed is Haman” (1). I heard a teaching on this from the holy mouth of my teacher and grandfather [Rabbi Yitzhak Meir], that one must go above the Tree of Knowledge of Good and Evil. Although I don’t exactly remember his words, it seems that he connected the “tree fifty cubits tall” (2) to the forty-nine gates of impurity, for there are forty-nine types of impurity and purity (3). The power of Amalek is found at every one of those forty-nine levels, but the fiftieth gate is that of holiness (4). There is no dualism there, but rather only good, for it is the root of unity. So it is written [about the war against Amalek], “when Moses raised his hands” — that is, to the fiftieth gate and the Tree of Life, which is the Torah — Israel would prevail, but when he let his hands fall, Amalek would prevail” (5).
1) Megillah 7b 2) that is, the post that Haman erected to hang or impale (depending on your translation) Mordechai, and on which Haman was himself executed; the word is eitz, the same as “tree” 3) a kabbalistic idea; according to tradition, while living in the exile of Egypt the Jews fell from one level of impurity to another, until on the eve of the redemption they were about to fall into the fiftieth and final level, from which there is no return (see Or HaHayyim on Exodus 3:7); the parallel phenomenon is the fifty gates of purity, through which we rise one by one as we count the Omer from Pesach to Shavuot, from Redemption to Revelation; there is also the parallel of the fifty gates of wisdom, the first forty-nine of which can be achieved through human effort, but the fiftieth of which only comes through divine grace, being above human comprehension. 4) Amalek is the leader (and the tribe) that tried to destroy the Children of Israel while wandering through the desert (Exodus 17:8-10), apparently for no reason but for the sake of murder, and so Amalek is considered the archetype of anti-Semites and pure evil. Haman is called an Agagite, that is, a descendant of Amalek, and is considered an incarnation of the same murderous evil. 5) Exodus 17:11