Class One. The world was created on the 25th of Elul which is special in so many ways, but we celebrate Rosh Hashana on 1 Tishrei, because of the revealing of G-dliness in the lower worlds. This is connected primarily to the נשמה, but the נשמה needs the body to bring it to this world. Revealing G-dliness on the level of the material as well. This is why the judgement is for physical things also on Rosh Hashana.
Class Two. This is why Rosh Hashana is connected to בנין המלכות. Four differences between מלכות and the other ספירות in various areas explain it’s loftiest of sources and descent to the lowest levels. All ספירות are renewed from their highest source on Rosh Hashana but only מלכות reveals the source itself.
