43a. Mashcheini (18 Elul) 5735, Class One. The Possuk משכני אחריך נרוצה הבאני המלך חדריו נגילה ונשמחה בך is always brought to explain the process of 1) leaving Mitzrayim (משכני לשון יחיד לנה”א בלבד), 2) preparing ourselves for meeting God getting the Torah and ‘becoming His betrothed’ (אחריך נרוצה לשון רבים) and 3) the actual event of Mattan Torah (הביאני המלך חדריו בבחי’ ישראל ומלכא בלחודוהי); Here the Rebbe applies it to Elul and Tishrei, 1) Rosh Chodesh Elul opens the 13 attributes of mercy [and is some kind of revelation (??)] (משכני) 2) after that Hashem hides and we seek Him because He is hiding (אחריך נרוצה לשון רבים), 3) and on Yom Kippur we get the Torah of Teshuva, the second Luchos (הביאני המלך חדריו), 4) On Simchas Torah all this comes out in overt Joy (נגילה ונשמחה בך). The parallel between using this Possuk for the summer holidays and the winter ones isn’t exact, because in the summer we follow after Him (chase Him) because He revealed Himself, and in Elul it’s because He hides from us.
