894. Simchat Torah [The Joy of Torah]
It is written in Shaar HaKavanot that Torah is called Zeir Anpin, and if he bestows upon Malchut, it means that Malchut is already fit to receive the abundance. Therefore, Zeir Anpin, who is called “Torah,” is happy.
This is called “the joy of Torah.” We can interpret this according to what Baal HaSulam said, that one should be happy that the Creator is happy that He can bestow upon the lower ones.