Jewish law prohibits imposing a celebration onto an already joyful time - a rule known as "ein me'arvin simcha besimcha". And yet, Simchat Torah, when we dance with the Torah scrolls having completed the reading of the entire Torah, appears to have been imposed onto the festival of Shmini Atzeret. Rabbi Dunner explains why this is not the case, and how Simchat Torah is the perfect vehicle for joy on Shmini Atzeret.