…והיית אך שמח
…and you shall be only joyous
There’s an interesting Midrash that compares the time between Pesach and Shavuos, and the time between Sukkos and Shemini Atzeres. The time between Pesach and Shavuos is fifty days, whereas there is no break between Sukkos and Shemini Atzeres. Why is this so? The Midrash answers with a parable. This is similar to a king with many kids. Some are married and live far away, and some are married and live close by. When those who live close by come to visit, when came time to depart the King would let them go without difficulty, since anyways they live close by. However, those who live far away, when they would visit and it came time to leave, the King would hold them back. He would plead with them to stay one more day, due to the distance between them.
The same is true with Pesach and Sukkos. Pesach is in the summer, and it’s easy to travel. When the Jews make their pilgrimage to Jerusalem and the Temple, after the Festival they can go on their way without issue. Hashem knows it will be easy for them to return for Shavuos, so the two Festivals aren’t consecutive. However, Sukkos is in the wintertime. It’s rainy, and the roads are muddy. It’s harder to travel, so Hashem would rather they stay for another Festival than make the hard journey twice. Therefore, Shemini Atzeres follows Sukkos without pause.
The Midrash continues and says that once the Jews heard this, that Hashem in His kindness made Shemini Atzeres easier for them, they began to praise Him. They said: “This is the day that Hashem made, let’s rejoice and be glad in Him!” Now, this raises a question. Shemini Atzeres is a Festival like any other Festival. All the Festivals have a mitzvah to rejoice. Even if Shemini Atzeres was fifty days after Sukkos, like Shavuos after Pesach, there would be an idea to rejoice. Why did the Jews decide to rejoice upon hearing that Hashem made it easier for them?
The Torah tell us, with regards to the Festival of Sukkos, that we shall be only joyous. Why does the Torah say this? The gemarra says it’s to teach us that even the night of Shemini Atzeres is obligated in the mitzvah of rejoicing. The gemarra questions this teaching and says that perhaps the verse comes to include even the first night of Sukkos in rejoicing, but not the night of Shemini Atzeres. The gemarra rebuffs this rejoinder and says that it makes more sense to include the night of Shemini Atzeres in rejoicing. Why? Since it is preceded by many days of rejoicing, it’s fitting to also be a night of rejoicing. This is unlike the first night of Sukkos, which has no days of rejoicing before it.
According to this then, the Midrash we started with makes perfect sense. The only reason we know there’s a concept of rejoicing on Shemini Atzeres night is because the Festival is immediately preceded by Sukkos. Had Shemini Atzeres been fifty days after Sukkos, like Shavuos is to Pesach, we wouldn’t have known to rejoice on Shemini Atzeres. Once the Jews heard that Shemini Atzeres is to follow immediately after Sukkos, they realized that it was a time to rejoice as well.
May we be only joyful this Festival. Chag Sameach and Gut Moed!
 Based on Chiddushei HaGriz HaChadashim § 61
 Deuteronomy 16:15
 Yalkut Shimoni Pinchas § 782 s.v. אתה מוצא. It is unsourced, but it seems to be taken from Pesikta D’Rav Kahana to Numbers 29:35 Nuscha Acheres s.v. דבר אחר למה נעצרו
 Yalkut Shimoni loc. cit. says נשואין and נשואים, whereas Pesikta D’Rav Kahana loc. cit. says נושאים. The latter is a language of carrying, perhaps implying some form of employment, nothing to do with marriage. Perhaps it’s a typo, and the Yalkut’s version is more correct
 Yalkut Shimoni loc. cit. s.v. דבר אחר יספת לגוי. This seems to be taken from Pesikta D’Rav Kahana Piska § 30 s.v. אמר רבי אלכסנדרי and Pesikta Rabbasi Hosafah 1 Piska 4 s.v. דבר אחר ביום השמיני. I’m not entirely sure why the Brisker Rav puts these two Midrashim together. Although they are in the same Remez in Yalkut Shimoni, they are clearly different Midrashim, discussing two different things. All I can gather is he must have been following in his father’s footsteps, as Rav Chaim in Chiddushei HaGrach to Sukkah 35b s.v. והנה בילקוט does the same thing
 See previous note. The second Midrash when it says “this”, is referring to Hashem requiring only one bull offering for Shemini Atzeres, unlike the multitude of offerings required on Sukkos. The Brisker Rav seems to understand that the general idea is the Jews were grateful that Hashem took it easy on them with Shemini Atzeres
 Psalms 118:24
 Pesachim 71a; Sukkah 48a
 Although, I would say the Midrash is discussing Shemini Atzeres day, as they said זה היום