Class Thirty Three in Section Four of The Source

בלילה ההוא ה’תשכ”ה. This class further explains the idea of עצם giving כח in this case as it relates to the “night” (darkness of Golus) of the Purim story. He explains two levels of העלם: 1) העלם בשביל הגילוי. 2) העלם מצד עצמו. The first idea is the traditional one and it is about revealing the light after the Tzimtzum. The second idea is about the עצם being revealed and what it achieves.