The laws of succah contain a striking inconsistency. Why are there different laws for the walls of the succah than for the ceiling? The walls of the succah can be made of virtually any material, even if it is m’kabel tumah, (able to contract impurity), while the ceiling of the succah (the s’chach) is limited to materials that cannot contract impurity (branches, bamboo, or shrubs). Why the difference? Many midrashim answer that the succah is analogous to Bnei Yisroel. We are composed of two components: the body and the soul – the mundane and the spiritual. A person is a being that engages in both the spiritual and the mundane on a daily basis. Occupying ones time in purely material activities would deprive the soul of its spiritual needs, while involving oneself solely in spiritual tasks would deprive the body a foundation to live in this world. The succah represents the balance a Jew demonstrates between these two responsibilities.
Throughout the calendar year, there is a balance struck between the everyday and the holy as well. The Slonimer Rebbe points out that the days of the year are broken up into periods of spiritual and periods of more mundane. Shemini Atzeret is a very special day in that it concludes a period of many holidays. It shares remarkable similarity to Shavuot, or Chag Ha’Atzeret as it is referred to in the torah. These two ‘Atzeret’s bare the root atzur, ‘to stop’, and are end points to a cluster of holidays. Shavuot, or Chag Ha’Atzeret is fifty one days following the first day of Pesach (1 day of Pesach, 49 days in Sfiras Ha’Omer, and Shavuot), and similarly Shemini Atzeret is the fifty first day after Rosh Chodesh Elul (29 days of Elul, 10 days from Rosh Hashana until Yom Kippur, 4 days until Succot, and 8 days of Succot including Shemini Atzeret). Besides this similarity, there is a striking inner connection between these two days.
The Slonimer Rebbe writes that the holiness of all the holidays escalate, culminating with these two days of ‘Atzeret’, which are the most holy. Seven is a number that corresponds to the natural cycle, while eight is a number representing one above nature. Both Shemini Atzeret and Shavuot share this characteristic of the number eight. Shemini Atzeret is the eighth and final day of Succot (in Israel) and Shavuot is the eighth day, following the counting of Sfiras Ha’omer, which is seven weeks of seven. These two days are ones in which Bnei Yisroel experience an extra closeness with Hashem. The medrash says (Vayikra 23:33 Rashi, Vayikra Rabba) that after the seven days of Succot, Hashem held Bnei Yisroel one day longer as a display of his closeness and love for us. Shavuot, also, commemorates a time in which Bnei Yisroel became especially close to Hashem, as they purified themselves to reach a level worthy of receiving the torah. Moreover, both these holidays share one more important theme- The Torah. On Shavuot we received it and on Shemini Atzeret/Simchat Torah we complete it each year.
Both these holidays of ‘Atzeret’ are not only conclusions of the holiday season, but also chances for us to stop as well. This is why neither Shemini Atzeret nor Shavuous have any specific mitzvos such as matzah by pesach, or lulav and succah by Succot. It is strictly a day for us to get closer to Hashem before the daily routine commences.