The Gemara in Rosh HaShana identifies the festival of Shmini Atzeres as a separate festival in its own right to Sukkos.
Why then, do we refer to the three festivals, when there are in fact four? The other festivals also have clearly stated reasons, commemorating specific events. What is Shmini Atzeres? What is the function of atzeres a chag?
The Nesivos Shalom explains that there are several unique aspects to the day. The Gemara in Sukka teaches that after the 7 day festival of Sukkos, Hashem says “stay a little longer so that I can enjoy your company some more”. In Kabbala, it is identified as the day where the final judgement is delivered and carried out. We also make it the day where we complete and restart the Torah cycle and dance and rejoice.
Why do these events happen on Shmini Atzeres particularly, marking it as different from other festivals, deserving its own category?
The answer can be found in exploring what the significance of the number 8 is. The Maharal explains that the number seven includes everything cyclical, physical and natural. There were 7 days of creation, corresponding to all of the nature contained within. The number 8 supersedes what comes before, 7, and refers to the metaphysical and spiritual, anything supernatural. It is a state above nature.
Anywhere the number 8 is mentioned it refers to a supernatural event. The Mishkan entered regular use on its’ 8th day, which the Gemora in Shabbos discusses as being a day where the prescience of God was so palpable that the whole area shone. Circumcision is done on the 8th day after a child is born. He becomes a fully fledged Jew.
So Shmini Atzeres isn’t like the other 3 festivals. It’s a day of supernatural exposure to God that it can’t be categorised together with the other festivals – all of which are 7 days or less, indicating their operation within nature. It is a day where we mark the completion of God’s gift to us, the Torah.
The other festivals celebrate a particular event in history, such as leaving Egypt. But Shmini Atzeres is a day of such joy that the Sages compared it to the happiness one experiences on their wedding day. All the festivals are a build up to the culmination that is Shmini Atzeres.
Starting at Selichos, the prayers of Ellul, we open the Ark for prayer. On Rosh HaShana this develops into opening the Ark many times, and on Yom Kippur, this develops further at to taking several Torah scrolls out and parading them, and the concluding service has the Ark kept open the entire time. On Hoshana Rabba we take out all the scrolls and stand at the front.
But then comes the crowning moment: Shmini Atzeres and Simchas Torah. We all dance with the Torah. It’s a day of such ecstasy and celebration that it is supernatural and thus categorised by the number 8, hence it’s name. It is truly in a category of its own, completely separate to the other festivals.